Comparative evaluation of rotational stability of toric IOLs with four-eyelet vs two-eyelet capsular tension rings in eyes with high myopia

AIM:To compare the rotational stability of Toric intraocular lens(IOLs)implantation combined with foureyelet or two-eyelet capsular tension rings(CTRs)in eyes with high myopia and cataract.METHODS:This prospective randomized controlled interventional study in cluded 33 eyes which had preoperative corneal astigmatism≥1.5 D and ocular axial length≥25.5 mm.These eyes were randomly divided into two groups to undergo phacoemulsification and toric IOL implantation with either four-eyelet CTR implantation(group A,n=16)or two-eyelet CTR implantation(group B,n=17).Uncorrected visual acuity(UCVA),best-corrected visual acuity(BCVA),phoropter examination results,and toric IOL rotation degrees were tested 6 mo after the surgery.RESULTS:In both groups,the toric IOL was in the capsular sac 6 mo after surgery.The difference between the two groups in terms of visual outcome was not found to be statistically significant(P>0.05)at a follow-up of 6 mo.The mean residual astigmatism values were 0.56±0.22 D and 0.92±0.24 D in A and B groups,respectively(P<0.001).The mean rotation degree of IOL was 1.00°±0.73°in group A and 3.53°±1.46°in group B(P<0.001).CONCLUSION:In cataract patients with high myopia and astigmatism,four-eyelet CTR can effectively increase the rotation stability of toric IOLs,achieving the desired goal of correcting corneal astigmatism.     

Prediction of Refractive Error in Combined Vitrectomy and Cataract Surgery With One-Piece Acrylic Intraocular Lens

Purpose

To compare the predicted and actual refractive errors of hydrophilic, one-piece, C-flex®570C (C-flex) intraocular lens (IOL) implantation in simultaneous vitrectomy and lens extraction in various conditions.

Methods

One hundred fifty-nine eyes of patients who had lens extraction between March 2004 and September 2005 were enrolled in a retrospective study. Group 1 had lens extraction and IOL implantation, and Group 2 had lens extraction and IOL implantation with vitrectomy. IOL calculation was done with axial length and keratometry measurements. The actual and predicted refractive errors were compared at 1 and 6 months postoperatively. The factors influencing the postoperative refractive outcomes were analyzed.

Results

The mean refractive predictive error (i.e., the actual minus predicted spherical equivalent) was +0.19±0.39 D (Diopter) and -0.26±0.45 D at 1 and 6 months postoperatively (all: p<0.001) in group 1, and -0.22±0.39 D and -0.06±0.62 D at 1 and 6 months postoperatively (p=0.013, p=0.399 respectively). In group 2, all surgical factors related to refractive errors were not statistically significant (all: p>0.05).

Conclusions

Refractive errors in combined surgery showed myopic shift of -0.50 D and -0.32 D at 1 and 6 months postoperatively compared with C-flex IOL implantation alone. With the hyperopic tendency of IOL and myopic tendency of vitrectomy, the combined surgery made postoperative refractive errors near emmetropia.     

Accuracy of axial length measurements from immersion B-scan ultrasonography in highly myopic eyes

AIM:To evaluate the accuracy of axial length (AL) measurements obtained from immersion B-scan ultrasonography (immersion B-scan) for intraocular lens (IOL) power calculation in patients with high myopia and cataracts.METHODS:Immersion B-scan, contact A-scan ultrasonography (contact A-scan), and the IOLMaster were used to preoperatively measure the AL in 102 eyes from 102 patients who underwent phacoemulsification and IOL implantation. Patients were divided into two groups according to the AL:one containing patients with 22 mm≤AL<26 mm(group A) and the other containing patients with AL≥26 mm (group B). The mean error (ME) was calculated from the difference between the AL measurement methods predicted refractive error and the actual postoperative refractive error.RESULTS:In group A, ALs measured by immersion B-scan (23.48±1.15) didn’t differ significantly from those measured by the IOLMaster (23.52±1.17) or from those by contact A-scan (23.38±1.20). In the same group, the standard deviation (SD) of the mean error (ME) of immersion B-scan (-0.090±0.397 D) didn’t differ significantly from those of IOLMaster (-0.095±0.411 D) and contact A-scan (-0.099±0.425 D). In group B, ALs measured by immersion B-scan (27.97±2.21 mm) didn’t differ significantly from those of the IOLMaster (27.86±2.18 mm), but longer than those measured by Contact A-scan (27.75±2.23 mm, P=0.009). In the same group, the standard deviation (SD) of the mean error (ME) of immersion B-scan (-0.635±0.157 D) didn’t differ significantly from those of the IOLMaster (-0.679±0.359 D), but differed significantly from those of contact A-scan (-0.953±1.713 D, P=0.028).CONCLUSION:Immersion B-scan exhibits measurement accuracy comparable to that of the IOLMaster, and is thus a good alternative in measuring AL in eyes with high myopia when the IOLMaster can’t be used, and it is more accurate than the contact A-scan.     

Combined 23-gauge microincisonal vitrectomy surgery and phacoemulsification with AcrySof toric intraocular lens implantation: a comparative study

Aim

To compare AcrySof toric intraocular lens (IOL) and non-toric IOL in patients who had combined 23-gauge microincisional vitrectomy surgery (MIVS) and phacoemulsification for vitreoretinal diseases and cataract with pre-existing corneal astigmatism.

Methods

This is a prospective comparative study comprised of 30 patients (30 eyes) who had combined 23-gauge MIVS and phacoemulsification for vitreoretinal diseases and cataract with pre-existing regular corneal astigmatism greater than 1 diopters (D). In all, 15 eyes had AcrySof toric IOL (Alcon Laboratories) and 15 eyes had non-toric IOL (Akreos AO MI60; Bausch & Lomb) implantation. Main outcome measures were uncorrected visual acuity (UCVA), refractive cylinder, surgically induced astigmatism (SIA), and IOL misalignment during 6 months.

Results

The mean UCVA of the toric IOL group was better than the non-toric IOL group at postoperative months 1, 3, and 6 (P<0.001, respectively). The mean absolute residual refractive cylinder of the toric IOL group at postoperative week 1, and months 1, 3, and 6 was less than the non-toric IOL group (P=0.008, <0.001, <0.001, and <0.001, respectively). There was no difference in the mean SIA between the two groups (P>0.05, respectively). The mean toric IOL axis rotation was 3.52±2.75°, which was within 5° in 66.7% of the toric IOL group and within 10° in 100%.

Conclusions

Combined 23-gauge MIVS and phacoemulsification with AcrySof toric IOL implantation is an effective method of correcting vitreoretinal diseases and cataract and pre-existing corneal astigmatism, and the toric IOL showed good rotational stability, even in vitrectomized eyes for 6 months.     

Optical quality of toric intraocular lens implantation in cataract surgery

AIM: To analyze the optical quality after implantation of toric intraocular lens with optical quality analysis system. METHODS: Fifty-two eyes of forty-four patients with regular corneal astigmatism of at least 1.00 D underwent implantation of AcrySof toric intraocular lens, including T3 group 19 eyes, T4 group 18 eyes, T5 group 10 eyes, T6 group 5 eyes. Main outcomes evaluated at 3mo of follow-up, included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), residual refractive cylinder and intraocular lens (IOL) axis rotation. Objective optical quality were measured using optical quality analysis system (OQAS Ⅱ?, Visiometrics, Spain), included the cutoff frequency of modulation transfer function (MTFcutoff), objective scattering index (OSI), Strehl ratio, optical quality analysis system value (OV) 100%, OV 20% and OV 9% [the optical quality analysis system (OQAS) values at contrasts of 100%, 20%, and 9%]. RESULTS: At 3mo postoperative, the mean UDVA and CDVA was 0.18±0.11 and 0.07±0.08 logMAR; the mean residual refractive cylinder was 0.50±0.29 D; the mean toric IOL axis rotation was 3.62±1.76 degrees, the mean MTFcutoff, OSI, Strehl ratio, OV 100%, OV 20% and OV 9% were 22.862±5.584, 1.80±0.84, 0.155±0.038, 0.76±0.18, 0.77±0.19 and 0.78±0.21. The values of UDVA, CDVA, IOL axis rotation, MTFcutoff, OSI, Strehl ratio, OV100%, OV20% and OV9% depending on the power of the cylinder of the implantation were not significantly different (P>0.05), except the residual refractive cylinder (P<0.05). CONCLUSION: The optical quality analysis system was useful for characterizing the optical quality of AcrySof toric IOL implantation. Implantation of an AcrySof toric IOL is an effective and safe method to correct corneal astigmatism during cataract surgery.     

Measurement of retinal thickness in macular region of high myopic eyes using spectral domain OCT

AIM:To investigate the changes of retinal thickness in macula of high myopic eyes using spectral domain optical coherence tomography (OCT).METHODS: Middle-aged and young myopic patients were divided into three groups according to their refractive error/axial length:low and medium myopia group (LMMG), high myopia group (HMG) and super high myopia group (SHMG). Cirrus HD-OCT was used to evaluate total average macular thickness, central subfield thickness, inner/outer macular thickness and macular volume. The differences among experimental groups were analyzed by one-factor analysis of variance. Associations between macular thickness and refractive error/axial length were analyzed by Pearson correlation analysis.RESULTS: There was no significant difference in age among the three groups (P=0.2789). The mean refraction error in the LMMG, HMG, and SHMG groups was -2.49±1.38D, -8.53±1.95D and -13.88±1.76D, respectively (P＜0.001). The central subfield thickness of three groups was 244.56±12.19μm, 254.33±11.61μm and 261.75±11.83μm, respectively, and there were statistically significance between random two groups. The total average macular thickness, inner/outer macular thickness, and macular volume decreased with increased myopia/axial length. Average foveal thickness had negative correlations with refractive error (P＜0.001), and positive correlations with axial length. The inferior and temporal inner macular thickness, all the quadrants of outer ring, total average macular thickness and macular volume featured positive correlations with refractive error, and negative correlations with axial length. Average foveal thickness, superior and temporal inner macular thicknesses, and temporal outer macular thickness was lower in females compared to males.CONCLUSION:With an increase in myopia degree/axial length, the average foveal thickness increased and the inner/outer macular thickness decreased. Females featured thicker average foveal thickness, and thinner macular thickness compared to males.     

Refractive Changes after Removal of Anterior IOLs in Temporary Piggyback IOL Implantation for Congenital Cataracts

Purpose

To assess the refractive change and prediction error after temporary intraocular lens (IOL) removal in temporary polypseudophakic eyes using IOL power calculation formulas and Gills'' formula.

Methods

Four consecutive patients (7 eyes) who underwent temporary IOL explantation were enrolled. Postoperative refractions calculated using IOL power calculation formulas (SRK-II, SRK-T, Hoffer-Q, Holladay, and the modified Gills'' formula for residual myopia and residual hyperopia) were compared to the manifest spherical equivalents checked at 1 month postoperatively.

Results

The mean ages of temporary piggyback IOL implantation and IOL removal were 6.71 ± 3.68 months (range, 3 to 12 months) and 51.14 ± 18.38 months (range, 29 to 74 months), respectively. The average refractive error was -13.11 ± 3.10 diopters (D) just before IOL removal, and improved to -1.99 ± 1.04 D after surgery. SRK-T showed the best prediction error of 1.17 ± 1.00 D. The modified Gills'' formula for myopia yielded a relatively good result of 1.47 ± 1.27 D, with only the variable being axial length.

Conclusions

Formulas to predict refractive change after temporary IOL removal in pediatric polypseudophakia were not as accurate as those used for single IOL implantation in adult eyes. Nonetheless, this study will be helpful in predicting postoperative refraction after temporary IOL removal.     

Lag of accommodation predicts clinically significant change of spherical equivalents after cycloplegia

AIM: To explore whether the retinal neovascularization (NV) in a genetic mutant mice model could be ameliorated in an inherited retinitis pigmentosa (RP) mouse, which would help to elucidate the possible mechanism and prevention of retinal NV diseases in clinic. METHODS: The Vldlr-/- mice, the genetic mutant mouse model of retinal NV caused by the homozygous mutation of Vldlr gene, with the rd1 mice, the inherited RP mouse caused by homozygous mutation of Pde6b gene were bred. Intercrossing of the above two mice led to the birth of the F1 hybrids, further inbreeding of which gave birth to the F2 offspring. The ocular genotypes and phenotypes of the mice from all generations were examined, with the F2 offspring grouped according to the genotypes. RESULTS: The rd1 mice exhibited the RP phenotype of outer retinal degeneration and loss of retinal function. The Vldlr-/- mice exhibited the phenotype of retinal NV obviously shown by the fundus fluorescein angiography. The F1 hydrides, with the heterozygote genotype, exhibited no phenotypes of RR or retinal NV. The F2 offspring with homozygous genotypes were grouped into four subgroups. They were the F2-Ⅰ mice with the wild-type Pde6b and Vldlr genes (Pde6b+/+-Vldlr+/+), which had normal ocular phenotypes; the F2-Ⅱ mice with homozygous mutant Vldlr gene (Pde6b+/+-Vldlr-/-), which exhibited the retinal NV phenotype; the F2-Ⅲ mice with homozygous mutant Pde6b gene (Pde6b-/--Vldlr+/+), which exhibited the RP phenotype. Specifically, the F2-Ⅳ mice with homozygous mutant Vldlr and Pde6b gene (Pde6b-/--Vldlr-/-) showed only the RP phenotype, without the signs of retinal NV. CONCLUSION: The retinal NV could be inhibited by the RP phenotype, which implies the role of a hyperoxic state in treating retinal NV diseases.     

Randomized trial comparing visual outcomes of toric intraocular lens implantation using manual and digital marker

Purpose:The aim of this study was to compare the visual outcome of participants undergoing toric intraocular lens (IOL) implantation after cataract extraction using manual marking versus digital marking for intraoperative guidance.Methods:Randomized controlled trial of participants with cataract and corneal astigmatism of 1.00 D-4.50 D. The eyes were grouped into manual marking (Group 1) and digital marking (Group 2). Preoperative Uncorrected distance visual acuity (UDVA), Corrected distance visual acuity (CDVA), and corneal astigmatism were determined. IOL power and axis of alignment were determined using Barrett toric calculator. Eyes were marked by bubble marker and Mendez ring in group 1 and by VERION (Alcon, Fort Worth, Texas) digital overlay in Group 2. Postoperatively, UDVA, CDVA, residual refractive cylinder and IOL misalignment were determined (iTrace system, Tracey technologies) at 1 week, 6 weeks, and 3 months.Results:A total of 61 eyes of 50 participants, 31 in Group 1 and 30 in Group 2, were studied. The mean postoperative cylindrical error was 0.50 ± 0.39 D in Group 1 and 0.29 ± 0.34 D in Group 2 (P = 0.03). 67.74% (n = 21) and 93.55% (n = 29) eyes achieved a residual astigmatism of ≤0.50 D and ≤1.00 D, respectively, in Group 1, whereas 83.33% (n = 25) and 100% (n = 30) eyes achieved a residual astigmatism of ≤0.50 D and ≤1.00 D, respectively, in Group 2 at 3 months postoperatively. Toric IOL misalignment was 4.71 ± 3.12° in Group 1 and 4.03 ± 2.99° in Group 2 (P = 0.39).Conclusion:Accurate manual marking and digital marking are equally effective guides for toric IOL alignment, intraoperatively.     

Protective effects of riboflavin-UVA-mediated posterior sclera collagen cross-linking in a guinea pig model of form-deprived myopia

AIM:To evaluate the effect of posterior sclera collagen cross-linking induced by riboflavin-ultraviolet A(UVA)on form-deprived myopia in guinea pigs.METHODES:Twenty-five pigmented guinea pigs of 3-week-old were randomly assigned into 4 groups that included normal control(NOR,n=7),form-deprived(FDM,n=7),normal with riboflavin-UVA cross-linking(NOR+CL,n=5)and form-deprived with cross-linking(FDM+CL,n=6).The NOR+CL group and the FDM+CL group received the riboflavin-UVA induced cross-linking at day 0.FDM was induced by monocularly deprived with facemask in the right eyes.The refraction,axial length and corneal curvature were measured by retinoscopy,A-scan and keratometer respectively in scheduled time points(day 0 and 1,2,3,4 wk after form-deprivation).At the end of 4 weeks’experiment,stress-strain tests of sclera were measured and morphological changes of sclera and retina were examined.RESULTS:After 4 wk,the interocular difference of refractive error were-0.11±0.67,-2.93±0.56,1.10±0.58,and-1.63±0.41 D in the NOR,FDM,NOR+CL,and FDM+CL groups respectively.Mixed-effect linear model revealed significant effect of FDM(P<0.01)and CL(P<0.001).Also,after 4 wk,the interocular difference of axial length were 0.01±0.04,0.29±0.07,-0.13±0.06,and 0.11±0.05 mm in the NOR,FDM,NOR+CL,and FDM+CL group.Mixedeffect linear model revealed significant effect of FDM(P<0.001)and CL(P<0.01).As for corneal curvature,significant interocular difference have not found between any of the two groups.At the end of this experiment,the ultimate stress and elastic modulus were found significantly increased in both CL groups.But no difference was found in the groups without cross-linked.There was no abnormality observed in the retina and RPE cells of the treated eyes.CONCLUSION:The posterior sclera collagen crosslinking induced by riboflavin-UVA can slow down the progress of myopia and increase the sclera biomechanical strength in the guinea pig model of form-deprived myopia.     

Clinical study of customized aspherical intraocular lens implants

AIM:To compare if there is an improvement in visual functions with age-related cataracts between patients receiving a aspherical intraocular lens (IOL) based on corneal wavefront aberration and patients randomly assigned lenses.METHODS:A total of 124 eyes of 124 patients with age-related cataracts were placed in experimental group and a group receiving randomly assigned (RA) lenses. The experimental group was undergone Pentacam corneal spherical aberration measurement before surgery; the targeted range for residual total spherical aberration after surgery was set to 0-0.3 μm. Patients with a corneal spherical aberration ＜0.3 μm were implanted with a zero-spherical aberration advanced optics (AO) aspherical IOL and patients with an aberration ≥0.3 μm received a Tecnis Z9003 aspherical lens in experimental group. RA patients were randomly implanted with an AO lens or a Tecnis Z9003 lens. Three months after surgery total spherical aberration, photopic/mesopic contrast sensitivities, photopic/mesopic with glare contrast sensitivities, and logMAR vision were measured.RESULTS:Statistical analysis on logMAR vision showed no significant difference between two groups (P=0.413). The post-surgical total spherical aberration was 0.126±0.097 μm and 0.152±0.151 μm in the experimental and RA groups, respectively (P=0.12). The mesopic contrast sensitivities at spatial frequencies of 6, 12 and 18 c/d in the experimental group were significantly higher than of the RA group (P=0.00; P=0.04; P=0.02). The mesopic with glare contrast sensitivity in the experimental group at a spatial frequency of 18 c/d was also significantly higher vs the RA group (P=0.01).CONCLUSION:Pre-surgical corneal spherical aberration measurement in cataract patients followed by customized selection of aspherical IOL implants improved mesopic contrast sensitivities at high spatial frequencies, and thus is a superior strategy compared to the random selection of aspherical IOL implants.     

Accuracy and reliability of IOL master and A-scan immersion biometry in silicone oil-filled eyes

Purpose

To compare the accuracy and reliability of intraocular lens (IOL) master and A-scan immersion biometry in silicone oil (SO)-filled eyes.

Methods

A prospective, consecutive, nonrandomized study was performed in 34 SO-filled eyes of 34 patients, who underwent a pars plana vitrectomy, with SO removal and cataract surgery, as well as IOL implantation. Both IOL master and immersion A-scan were performed to measure the axial length (AXL) before SO removal. Three months after removal of the SO, AXL measurements using IOL master and refraction was performed. Accuracy of the two techniques was determined by a mean postoperative AXL using an IOL master and reliability was determined by mean actual postoperative refractive error.

Results

Preoperative mean AXL was 23.91±0.24 mm (range 21.33–28.61 mm) and 23.71±0.59 mm (range 19.27–36.18 mm) by IOL master and A-scan immersion, respectively. Postoperative mean AXL by IOL master was 23.90±0.23 mm (range 21.58–27.94 mm), which showed a statistically significant difference from the preoperative mean AXL by A-scan immersion (P=0.005). The AXL measurement by IOL master also was more accurate than A-scan immersion by Pearson''s correlation (0.966 vs 0.410). For reliability of the two techniques, the predictive postoperative refractive error in A-scan immersion (mean 1.79±1.04 D, range −14.62 to 16.41 D) was greater than that in IOL master (mean 0.60±0.23 D, range −2.74 to 2.33 D), with a statistically significant difference (P=0.049).

Conclusion

IOL master had more accuracy and less deviation in predictive postoperative refractive error than A-scan immersion in SO-filled eyes.     

Phakic intraocular lenses outcomes and complications: Artisan vs Visian ICL

Purpose

To evaluate the safety and visual outcomes of two phakic intraocular lenses (IOLs) for correction of high myopia: Artisan and Visian ICL (ICL).

Patients and methods

In this retrospective study, a phakic IOL was implanted in 68 highly myopic eyes of 34 patients; 42 eyes received an Artisan IOL, and 26 eyes received ICL IOL.

Results

All patients completed a 1-year follow-up. The mean preoperative spherical equivalent (SEQ) was −12.89±3.78, and −12.44±4.15 diopters (D) for Artisan and ICL (P=0.078), respectively. The mean postoperative (1-year) uncorrected distance visual acuity was 0.39±0.13 and 0.41±0.15 logMAR for Artisan and ICL, respectively (P=0.268). The mean postoperative (1-year) corrected distance visual acuity was 0.36±0.12 and 0.31±0.12 logMAR for Artisan and ICL, respectively (P=0.128). The mean postoperative SEQ was −0.86±0.5 and −0.63±0.38 D for Artisan and ICL, respectively (P=0.67). Intraocular pressure change at 1 year was 0.64±2.7 and 1.88±0.6 mm Hg for Artisan and ICL, respectively (P=0.77).

Conclusion

Artisan and ICL showed equal and comparable safety, predictability, and efficacy.     

Comparative analysis of predictability and accuracy of American Society of Cataract and Refractive Surgery online calculator with Haigis-L formula in post-myopic laser-assisted in-situ keratomileusis refractive surgery eyes

Purpose:The aim of this study was to compare the predictability and accuracy of the American Society of Cataract and Refractive Surgery (ASCRS) online calculator with the Haigis-L formula for intraocular lens (IOL) power calculation in post myopic laser-assisted in-situ keratomileuses (LASIK) eyes undergoing cataract surgery and also to analyze the postoperative refractive outcome among the ASCRS average, maximum and minimum values.Methods:A retrospective study was conducted on post myopic LASIK eyes which underwent cataract surgery between June 2017 and December 2019. IOL power was calculated using both Haigis-L & ASCRS methods. Implanted IOL power was based on the ASCRS method. The expected postoperative refraction for IOL power based on the Haigis-L formula was calculated and compared with the Spherical Equivalent (SE) obtained from the patient''s actual refraction. Prediction error (PE) & Mean Absolute Error (MAE) was calculated. Intragroup analysis of ASCRS values was done.Results:Among the 41 eyes analyzed, pre-operative and post-operative mean best-corrected visual acuity was 0.58 ± 0.21 and 0.15 ± 0.26 logMAR, respectively. In the ASCRS method, 36 (87.8%) and 40 (97.6%) eyes had PE within ± 0.5D and ± 1.0 D, respectively, whereas, in the Haigis-L method, 29 (70.7%) eyes, and 38 (92.7%) eyes had PE within ± 0.5D and ± 1.0 D, respectively. Among the ASCRS subgroups, ASCRS average, maximum and minimum values had 83%, 80.6%, and 48.8% eyes with SE within ± 0.5D, respectively.Conclusion:ASCRS method can be considered as an equally efficient method of IOL power calculation as the Haigis-L method in eyes which have undergone post myopic LASIK refractive surgery. ASCRS maximum & average values gave better emmetropic results.     

Predictive factor and kappa angle analysis for visual satisfactions in patients with multifocal IOL implantation

Purpose

To evaluate the visual acuity and quality-related satisfaction of patients implanted with a refractive design multifocal intraocular lens (IOL), and evaluate the factors predicting it including angle kappa.

Setting

Dr Agarwal''s Eye Hospital and Eye Research Centre, Chennai.

Methods

In this prospective trial, 50 eyes of 44 consecutive patients were included. All patients underwent phacoemulsification with multifocal IOL implantation (Rezoom IOL, Abbott Medical Optics). The preoperative and postoperative assessment included slit lamp biomicroscopy, uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA) and kappa angle assessment. At 1 year, 37 patients (43 eyes), who finished follow-up, were asked to rate their symptoms on a graded questionnaire (0–5 for five queries).

Results

The decimal scores for UCVA and BCVA were 0.38±0.21 and 0.47±0.17 (preoperative), and 0.75±0.22 and 0.99±0.11 (postoperative), respectively. Symptom scores were haloes 0.98±1.7, glare 0.69±1.48, blurred distance 1.0±1.7, intermediate 1.34±1.6, near 1.06±1.8. On regression analysis haloes depended on angle kappa and distance UCVA (R ²=0.26, P=0.029), and glare on angle kappa (R ²=0.26, P=0.033). Poor satisfactions with distance, intermediate, and near vision were linked with distance UCVA (R ²=0.17, P=2.3 × 10⁻⁴), distance UCVA (R ²=0.1, P=0.04), and near UCVA (R ²=0.12, P=0.03), respectively. The strongest predictor, however, for overall visual discomfort was distance UCVA (R ²=0.1, P=0.04).

Conclusions

Our study suggests that there may be a role of misalignment between the visual and pupillary axis (angle kappa) in the occurrence of photic phenomenon after refractive multifocal IOL implantation.     

Evaluation of intrastromal corneal ring segments for treatment of post-LASIK ectasia patients with a mechanical implantation technique

Aim:

To evaluate the clinical outcomes of Keraring segment implantation in patients with post- laser-assisted in situ keratomileusis (LASIK) ectasia, using a mechanical implantation technique.

Materials and Methods:

Twelve eyes of 10 patients with post-LASIK ectasia were enrolled. Intracorneal ring segments (ICRS) were implanted after dissection of the tunnel using Tunc''s specially designed dissector under suction. A complete ophthalmic examination was performed, including uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent, keratometric (K) readings, inferosuperior asymmetry index (ISAI), and ultrasound pachymetry. All 3, 6, and 12-month follow-ups were completed, and statistical analysis was performed.

Results:

The mean preoperative UDVA for all eyes was 1.28 ± 0.59 logMAR. At 12 months, the mean UDVA was 0.36 ± 0.19 logarithm of the Minimum Angle of Resolution (logMAR) (P=0.002), and the mean preoperative CDVA was 0.58 ± 0.3 logMAR, which improved to 0.15 ± 0.12 (P=0.002) at 1 year. There was a significant reduction in cylindrical refractive and spherical equivalent refractive error from –5.29 ± 2.47 diopters (D) and –5.54 ± 5.04 D preoperatively to –1.47 ± 0.71 D and –0.74 ± 1.07 D (P=0.001, P=0.002), respectively, at 1 year. In the same period, the mean K- readings improved from 47.93 ± 4.84 D to 40.87 ± 2.36 D (P=0.002), and the mean ISAI improved from 5.34 ± 3.05 to 2.37 ± 1.68 (P=0.003). No significant changes in mean central corneal thickness were observed postoperatively. There were no major complications during or after surgery.

Conclusion:

ICRS implantation using a unique mechanical dissection technique is a safe and effective treatment for post-LASIK ectasia. All parameters showed improvement at 1-year follow-up.     

Laser in-situ keratomileusis for refractive error following radial keratotomy

Aim:

To evaluate the safety and efficacy of laser in-situ keratomileusis (LASIK) in eyes with residual/induced refractive error following radial keratotomy (RK).

Design:

Retrospective study.

Materials and Methods:

A retrospective analysis of data of 18 eyes of 10 patients, who had undergone LASIK for refractive error following RK, was performed. All the patients had undergone RK in both eyes at least one year before LASIK. Parameters like uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), contrast sensitivity, glare acuity and corneal parameters were evaluated both preoperatively and postoperatively.

Statistical Software:

STATA-9.0.

Results:

The mean UCVA before LASIK was 0.16±0.16 which improved to 0.64 ± 0.22 (P < 0.001) after one year following LASIK. Fourteen eyes (out of 18) had UCVA of ≥ 20/30 on Snellen''s acuity chart at one year following LASIK. The mean BCVA before LASIK was 0.75 ± 0.18. This improved to 0.87 ± 0.16 at one year following LASIK. The mean spherical refractive error at the time of LASIK and at one year after the procedure was –5.37 ± 4.83 diopters (D) and –0.22 ± 1.45D, respectively. Only three eyes had a residual spherical refractive error of ≥ 1.0D at one year follow-up. In two eyes, we noted opening up of the RK incisions. No eye developed epithelial in-growth till 1 year after LASIK.

Conclusion:

LASIK is effective in treating refractive error following RK. However, it carries the risk of flap-related complications like opening up of the previously placed RK incisions and splitting of the corneal flap.     

Intraocular lens power calculation using IOLMaster and various formulas in short eyes

Purpose

To evaluate the predictability of intraocular lens (IOL) power calculations using the IOLMaster and four different IOL power calculation formulas (Haigis, Hoffer Q, SRK II, and SRK/T) for cataract surgery in eyes with a short axial length (AL).

Methods

The present study was a retrospective comparative analysis which included 25 eyes with an AL shorter than 22.0 mm that underwent uneventful phacoemulsification with IOL implantation from July 2007 to December 2008 at Seoul National University Boramae Hospital. Preoperative AL and keratometric power were measured by the IOLMaster, and power of the implanted IOL was determined using Haigis, Hoffer Q, SRK II, and SRK/T formulas. Postoperative refractive errors two months after surgery were measured using automatic refracto-keratometry (Nidek) and were compared with the predicted postoperative power. The mean absolute error (MAE) was defined as the average of the absolute value of the difference between actual and predicted spherical equivalences of postoperative refractive error.

Results

The MAE was smallest with the Haigis formula (0.37 ± 0.26 diopter [D]), followed by those of SRK/T (0.53 ± 0.25 D), SRK II (0.56 ± 0.20 D), and Hoffer Q (0.62 ± 0.16 D) in 25 eyes with an AL shorter than 22.0 mm. The proportion with an absolute error (AE) of less than 1 D was greatest in the Haigis formula (96%), followed by those in the SRK II (88%), SRK-T (84%), and Hoffer Q (80%).

Conclusions

The MAE was less than 0.7 D and the proportion of AE less than 1 D was more than 80% in all formulas. The IOL power calculation using the Haigis formula showed the best results for postoperative power prediction in short eyes.     

Outcomes of early versus deferred laser after intravitreal ranibizumab in aggressive posterior retinopathy of prematurity

Purpose:The aim of this study was to report the treatment outcomes of early and deferred laser in infants of aggressive posterior retinopathy of prematurity (APROP) after initial treatment with intravitreal Ranibizumab (IVR).Methods:In a prospective, randomized, interventional study, infants with APROP received IVR (0.25 mg) and were randomized into two groups prior to laser. Laser was done at 1 week (group 1) or at 6 weeks or earlier if there was a recurrence of plus disease (group 2). The structural outcome, number of laser spots, duration of laser procedure and refractive error at 6 months were compared. Favorable structural outcome was defined as, complete regression of disease at 6 weeks after laser.Results:63 eyes of 32 infants with APROP were enrolled. Mean gestational age (GA) and birth weight (BW) were 30.2 ± 2.3 weeks and 1294 ± 372.8 grams respectively. GA, BW, and disease severity were comparable at baseline. 27 (90%) eyes in group 1 and 29 (93.5%) eyes in group 2 had favorable structural outcome (P = 0.61) at 6 weeks after laser. Eyes in group 2 (2149.8 ± 688.7) required lesser number of laser spots than group 1 (2570.8 ± 615) (P = 0.01). At six months, more eyes in group 1 had myopic refractive error (Mean spherical equivalent: –1.0D ± 1.3) than those in group 2 (Mean spherical equivalent: 0.5D ± 1.9) (P = 0.002).Conclusion:Infants with APROP receiving IVR have comparable structural outcomes after an early or deferred laser. Moreover, eyes undergoing deferred laser require less number of laser spots and have a less myopia at 6 months after laser.     

Intraocular lens power calculation after myopic and hyperopic laser vision correction using optical coherence tomography

Purpose

To use optical coherence tomography (OCT) to measure corneal power and calculate intraocular lens (IOL) power in cataract surgeries after myopic and hyperopic laser vision correction (LVC).

Methods

Patients with previous LVC were enrolled in this prospective study at two centers (Doheny Eye Institute, Los Angeles, CA, USA and Cullen Eye Institute, Houston, TX, USA). Corneal power was measured with a Fourier-domain OCT system. The intravisit repeatability of OCT corneal power measurement was evaluated by the pooled standard deviation of repeat scans. Axial length, anterior chamber depth, and automated keratometry were measured with the IOLMaster. An OCT-based IOL formula was developed. The mean absolute error (MAE) of refractive prediction for OCT-based IOL formula was calculated. The results were compared with the MAE for Haigis-L formula.

Results

A total of 31 eyes of 24 subjects who had uncomplicated cataract surgery with monofocal IOL implantation were enrolled in the two sites. Twenty-two eyes of 16 subjects had previous myopic LVC that ranged from −12.46 D to −0.88 D. Nine eyes of 8 subjects had previous hyperopic LVC that ranged from 0.66 D to 5.52 D. The intravisit repeatability of OCT corneal power measurement was 0.24 D. For the myopic LVC group, the OCT formula had a MAE of 0.57 D compared to an MAE of 0.73 D for the Haigis-L formula (p = 0.19). For the hyperopic LVC group, the MAE for OCT and Haigis-L formula was 0.26 D and 0.54 D, respectively (p > 0.05).

Conclusions

Corneal power can be precisely measured with OCT. The predictive accuracy of OCT-based IOL power calculation is equal to current standards for post-LVC eyes.