Clinical outcomes between optical path difference custom aspheric treatment and optimized prolate ablation photorefractive keratectomy in myopia exceeding 8 diopters

Purpose

Comparison of visual acuity, refractive, and wavefront outcomes associated with optimized prolate ablation (OPA) and optical path difference custom aspheric treatment (OPDCAT) algorithms for correction of myopia exceeding 8 diopters (D).

Patients and Methods

Patients were randomly assigned to have photorefractive keratectomy (PRK) with OPA (n=32) or OPDCAT (n=21) algorithms. Visual acuity, manifest refraction, ocular and corneal higher-order aberrations, corneal asphericity, modulated-transfer function, and point-spread function were compared 1, 3, and 6 months postoperatively.

Results

Mean manifest-refraction spherical equivalents at 6 months were −0.24 D in both groups. All patients in both groups had an uncorrected-distance visual acuity of 20/20 or better. Predictability (±1 D from intended refraction) at 6 months was 94% in the OPA group, and in the OPDCAT group it was 86%. The OPA group had less induced corneal and ocular spherical aberrations (SAs) than the OPDCAT group. Postoperative corneal asphericity change was lowest in the OPA group. Both the groups exhibited significantly-improved AreaRatio-Total value and insignificantly deteriorated AreaRatio-HO value throughout the postoperative period. The OPA group had significantly-higher AreaRatio-Total compared with OPDCAT group at both 1 and 6 months after the operation. Six months after surgery, the Strehl ratio had decreased in both groups, and there was no significant difference between the groups.

Conclusion

The OPA algorithms yielded higher-objective visual quality and predictability, induced less corneal and ocular SAs, and preserved more preoperative-corneal asphericity than the OPDCAT algorithms.     

Die asphärische Blaulichtfilter-IOL AcrySof IQ im Vergleich mit der AcrySof SA60AT

Background

The aspheric optic design of intraocular lenses (IOL) aims to minimize postoperative ocular spherical aberration (SA). The effect of a standardized IOL asphericity depends on IOL power, pupil diameter, and corneal asphericity. The impact of these factors was investigated in a comparative study.

Material and methods

In a prospective study, 70 eyes with the aspheric blue light filter IOL AcrySof IQ (Alcon) were compared to 36 eyes with the conventional AcrySof SA60AT (Alcon). Six weeks after uneventful phacoemulsification the following parameters were assessed: visual acuity, higher order aberrations, pupil diameter, and corneal asphericity.

Results

The comparison of 42 eyes in a normal dioptric range with the IQ IOL (22.4±2.0 D) to 20 eyes with the control lens of similar IOL power (22.0±2.7 D) showed no different visual outcome. For a 5-mm pupil SA was calculated at 0.04 (±0.05) µm for the IQ IOL and 0.20 (±0.06) µm for the AcrySof SA60AT. Also for a 4-mm pupil SA was significantly lower in eyes with the IQ lens. A separate evaluation of 28 eyes which needed very high or low IOL power revealed a similar postoperative SA for the IQ IOL. The greatest difference of SA between the two IOLs was found in hyperopic eyes with higher IOL power. The corneal asphericity (Q value) showed significant correlation to postoperative ocular SA.

Conclusions

The aspheric AcrySof IQ reduces postoperative SA significantly compared to a conventional IOL even with smaller pupils and independent of IOL power. The assessment of corneal asphericity enables an individual estimation of postoperative SA.     

Topographic- and wavefront-guided customized ablations with the NIDEK-EC5000CXII in LASIK for myopia

PURPOSE: To assess refractive outcomes, changes in the total higher order root mean square (RMS) aberration, and changes in higher order wavefront aberrations after LASIK for myopia and myopic astigmatism with the NIDEK Advanced Vision Excimer Laser platform (NAVEX) using either an aspheric or topography-based or whole eye wavefront ablation algorithm. METHODS: This was a retrospective study of 1459 eyes that underwent LASIK for myopia and myopic astigmatism. The mean preoperative spherical equivalent refraction was -4.68 diopters (D) (range: -0.50 to -9.63 D) with astigmatism up to -4.50 D. Treatments were classified into three categories depending on the type of ablation algorithm used--optimized aspheric transition zone (OATz) denoted eyes that underwent aspheric treatment zones; customized aspheric treatment zone (CATz) denoted eyes that underwent customized ablations based on corneal topography; and OPDCAT denoted eyes that underwent customized ablation based on the whole eye wavefront profile. Follow-up data are reported at 3 months (69%) and 12 months (17%) postoperatively. RESULTS: Three months after LASIK, the predictability (10.5 D from target refraction) was 80% for OATz, 91% for CATz, and 76% for OPDCAT. Of all eyes, 96% were within +/- 1.0 D of intended refraction 3 months postoperatively and 100% after 12 months (87% +/- 0.5 D). In the aspheric and custom groups, a notable improvement of uncorrected visual acuity was noted between 3 and 12 months after LASIK. No eye lost >1 line of best spectacle-corrected visual acuity. Mean higher order RMS increased in all groups. CONCLUSIONS: The data support that the treatment of myopia and myopic astigmatism is safe and effective with NAVEX. Customized ablation based on corneal topography rather than on total wavefront error was more predictable.     

Aspheric wavefront-guided versus wavefront-guided LASIK for myopic astigmatism with the Technolas 217z100 excimer laser

Purpose

To compare clinical outcomes of wavefront-guided LASIK with and without aspheric compensation in myopic eyes.

Methods

In this observational, single-center study, 134 eyes were treated using an aspheric module in combination with wavefront-guided profiles (PTA-algorithm) and compared to 146 eyes treated with the predecessor wavefront-guided software (APT) that has no aspheric compensation. All treatment plans included the Rochester nomogram that accounts for the preoperative manifest refraction and interaction of higher order aberrations. Active eye-tracking (including cyclorotational movements) was utilized during photoablation.

Results

Results at the 3-month follow-up: 67 % of PTA-treated eyes and 39 % of APT-treated eyes achieved an uncorrected distance visual acuity (UDVA) of 20/20 or better. Change in mean higher order aberration root-mean-square (HOA RMS) after PTA treatments was not statistically significant (p?=?0.18). The increase in HOA RMS after APT treatments was statistically significant (p?=?0.003). Change in mean postop spherical aberration (SA) after PTA treatments was not statistically significant (p?=?0.27). The change in SA after APT treatments was statistically significant (p?=?0.001). In both cohorts, mean uncorrected low-contrast visual acuity was statistically not different to preoperative corrected values.

Conclusions

Adding an aspheric compensation to wavefront-guided myopic LASIK statistically improved clinical results in terms of visual acuity and refractive outcomes. Low-contrast visual acuity was not negatively affected in either group. While in APT-treated eyes mean HOA RMS and mean SA were significantly increased postoperatively, PTA-treated eyes showed neither induced HOA RMS nor induced SA.     

Einfluss der kornealen Biomechanik auf die Myopieregression nach Laser-in-situ-Keratomileusis

Background

Laser in situ keratomileusis is a safe and accepted method for correcting myopia. The operational results in terms of accuracy as well as the subjective acceptance of patients for corrections to – 8 D are now considered to be promising (Seiler, Refraktive Chirurgie der Hornhaut, 2000); however, postoperative results show individual patient problems in long-term stability. It is believed that the preoperative condition of the cornea (e.g. thickness, biomechanical properties) could have an influence on postoperative problems such as myopic regression.

Method

This study included a total of 46 eyes from 25 patients. At 3 months postoperatively, 15 patients (19 eyes) showed a SEQ of ??0.50 D or more. Within this group, 11 patients (15 eyes) developed a regression (regression group) within the first 3 postoperative months. The remainder of the total group did not show any regression (stability group). The subjects of this study were on average 33?±?8 years (stability group) and 31?±?7 years old (regression group). The corneal thickness was tested and refractive error, visual acuity (BCVA/UCVA) and intraocular pressure was measured. In addition, the corneal hysteresis (CH) and corneal resistance factor (CRF) were determined.

Results

The mean preoperative spherical equivalent refraction was ??3.14 D?±?1.41 D (SE) in the stability group and ? 6.47 D?±?1.40 D (p?=?0.001)in the regression group. Also, the postoperative spherical equivalents were statistically significant different (p?<?0.05). In contrast, the mean preoperative corneal thickness showed no differences in both groups (p?=?0.96) (stability group 563?±?36 µm and regression group 563?±?28 µm).

Conclusions

The aim of the study to detect a possible causal relationship between myopia regression after LASIK and the biomechanical properties of the cornea and corneal thickness could not be clearly identified.     

Evaluation of corneal epithelial and stromal thickness in keratoconus using spectral-domain optical coherence tomography

Purpose

We sought to assess the corneal thickness of the epithelium and stroma in keratoconic and normal eyes by spectral-domain optical coherence tomography (SD-OCT).

Methods

Fifty-seven keratoconic and 20 normal eyes were studied. The eyes were examined by SD-OCT, and the keratoconic eyes were subdivided into 2 groups: those showing only smooth corneal thinning and corneal protrusion on the image (KC1 group) and those showing abnormalities in the Bowman layer or in the stroma, or in both (KC2 group). The thicknesses at the corneal vertex and at the superior, inferior, nasal, and temporal cornea 1.5 mm from the corneal vertex in the KC1 group were compared with those in the normal group. The OCT findings in the KC2 group were described.

Results

The epithelial thickness at the corneal vertex and at the inferior and temporal cornea, and the stromal thickness at all points were significantly thinner in the KC1 group than in the normal group (p < 0.05). The epithelial and stromal thicknesses at the corneal vertex were significantly correlated in the KC1 group and the normal group (r ²  = 0.427, p < 0.0001).The epithelial thickness in the KC2 group was not uniform owing to Bowman layer scarring, stromal scars, and secondary corneal amyloidosis.

Conclusions

Although epithelial thinning is associated with stromal thinning, when the cornea remains clear, the epithelial thickness may vary because of the irregularity of the stroma beneath the epithelium in patients with keratoconus.     

A comparison between Goldmann applanation tonometry and dynamic contour tonometry after photorefractive keratectomy

Background

The intraocular pressure (IOP) could be measured by both Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT). Although these two methods have been discussed widely after laser-assisted sub-epithelial keratectomy (LASIK), there is little data in the cases undergoing photorefractive keratectomy (PRK). We aimed to compare the changes of IOP measurements obtained by GAT and DCT after PRK for myopia/myopic astigmatism.

Methods

This prospective study enrolled 77 candidates (154 eyes) for PRK to correct myopia or myopic astigmatism and 30 matched patients (30 eyes) with myopia or myopic astigmatism who served as controls. Changes of the IOP measurements (ΔIOP) obtained by GAT and DCT before and at 6 months after PRK in the operated eyes, and at baseline and 6 months later in the controls, were documented. Changes of the central corneal thickness (ΔCCT) were determined in the same fashion.

Results

The mean IOP readings obtained by DCT were comparable before and at 6 months after procedure (18.34 ± 3.03 mmHg and 17.87 ± 2.61 mmHg respectively, p?=?0.41); whereas the mean IOP reading obtained by GAT decreased significantly 6 months postoperatively (17.92 ± 3.63 mmHg and 16.25 ± 2.66 mmHg, p?<?0.001). A significant correlation was present between the ΔIOP obtained by GAT and ΔCCT (r?=?0.61, p?<?0.001). Similar correlation was not significant between the DCT-obtained ΔIOP and the ΔCCT (r?=?0.07, p?=?0.44). The mean ΔIOP obtained by GAT was significantly higher in the operated eyes than in the controls (?1.54?±?1.45 vs 0.07?±?0.44 mmHg, p?=?0.02). The mean DCT-obtained ΔIOP was just marginally insignificant between the operated and nonoperated eyes (?0.63?±?0.59 vs 0.02?±?0.38 mmHg respectively; p?=?0.09).

Conclusions

The authors recommend DCT after PRK in the cases with myopia or myopic astigmatism     

Refractive lenticule extraction (ReLEx flex) and wavefront-optimized Femto-LASIK: comparison of contrast sensitivity and high-order aberrations at 1 year

Aim

To compare 1-year results of the refractive lenticule extraction (ReLEx) flex technique performed as a commercial bilateral simultaneous procedure to a matched group of wavefront-optimized Femto-Lasik for correction of myopia and astigmatism with emphasis on contrast sensitivity and high-order aberrations (HOA).

Methods

In this retrospective study 44 eyes of 22 patients with spherical equivalent (SE) of ?5.13 D who underwent ReLEx were matched to 50 eyes of 25 patients with SE of ?5.42 D treated by wavefront-optimized Femto-Lasik. We used Carl Zeiss Meditec (CZM) VisuMax^® femtosecond laser system with a 200 kHz repetition rate. In addition, for Femto-LASIK, MEL 80 Excimer Laser (CZM) with aspheric ablation profiles was used for ablation.

Results

At 1 year, the mean SE in the ReLEx group was ?0.23 ± 0.35 D and in the Femto-LASIK group ?0.15 ± 0.27 D. The mesopic contrast sensitivity of ReLEx treated eyes at 12 and 18 cpd improved from 1.49 and 0.99 to 1.54 and 1.1 respectively. In the Femto-LASIK group the numbers were pre-op 1.51 and 1.03, and after 1 year 1.54 and 1.06. The high-order aberrations (HOA) after ReLEx changed from 0.15 to 0.23 μm, and after Femto-LASIK from 0.175 to 0.320 μm (p = 0.0023).

Conclusion

At 1 year, wavefront-optimized Femto-LASIK produced similar refractive outcomes to ReLEx^® flex with better, but non-significant accuracy. In contrast, ReLEx^® flex showed significantly less induction of HOA and better mesopic mid-term contrast sensitivity then the wavefront-optimized Femto-LASIK.     

Klinische Ergebnisse unter besonderer Berücksichtigung von Dezentrierung und Verkippung der asphärischen Intraokularlinse FY-60AD

Background

Aspheric intraocular lenses (IOLs) aim to improve visual function and particularly contrast vision by neutralizing spherical aberration. One drawback of such IOLs is the enhanced sensitivity to decentration and tilt, which can deteriorate image quality.

Methods

A total of 30 patients who received bilateral phacoemulsification before implantation of the aspheric lens FY-60AD (Hoya) were included in a prospective study. In 25 of the patients (50 eyes) the following parameters could be assessed 3 months after surgery: visual acuity, refraction, contrast sensitivity, pupil size, wavefront errors and decentration and tilt using a newly developed device.

Results

The functional results were very satisfying and comparable to results gained with other aspheric IOLs. The mean refraction was sph + 0.1 D (±0.7 D) and cyl 0.6 D (±0.8 D). The spherical equivalent was ?0.2 D (±0.6 D). Wavefront measurements revealed a good compensation of the corneal spherical aberration but vertical and horizontal coma also showed opposing values in the cornea and IOL. The assessment of the lens position using the Purkinje meter demonstrated uncritical amounts of decentration and tilt. The mean amount of decentration was 0.2 mm±0.2 mm in the horizontal and vertical directions. The mean amount of tilt was 4.0±2.1° in horizontal and 3.0±2.5° in vertical directions.

Conclusions

In a normal dioptric power range the aspheric IOL FY-60AD compensates the corneal spherical aberration very well with only minimal decentration. The slight tilt is symmetrical in both eyes and corresponds to the position of the crystalline lens in young eyes. This may contribute to our findings of compensated corneal coma.     

Comparison of corneal sensitivity between FS-LASIK and femtosecond lenticule extraction (ReLEx flex) or small-incision lenticule extraction (ReLEx smile) for myopic eyes

Background

To compare the effect on corneal sensitivity between femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) and femtosecond lenticule extraction (ReLEx flex) or FS-LASIK and small-incision lenticule extraction (ReLEx smile) surgery.

Methods

Twenty-seven subjects (54 eyes) underwent FS-LASIK, 22 subjects (40 eyes) underwent ReLEx flex, and 32 subjects (61 eyes) underwent ReLEx smile surgery. Cochet-Bonnet esthesiometry (Luneau Ophthalmologie Chartres, Cedex, France) was used to evaluate corneal sensitivity preoperatively as well as at 1 week and 1 and 3 months after surgery.

Results

At 1 week, central, superior, nasal, and temporal corneal sensitivity in the ReLEx flex group was significantly higher than in the FS-LASIK group (P?=?0.007, 0.004, 0.020, 0.004 respectively) and in the central and inferior areas at 3 months (P?=?0.002, 0.009 respectively). A higher corneal sensitivity after ReLEx smile surgery was observed in every quadrant at 1 week and 1 and 3 months compared with FS-LASIK surgery (P?<?0.01). Furthermore, in the ReLEx smile group, there were no statistical differences in the superior and temporal quadrants at 1 month postoperatively compared with preoperatively (5.19?±?0.61 cm, P?=?0.198 and 5.64?±?0.48 cm, P?=?0.330 respectively) and no significant differences in any quadrant at 3 months.

Conclusions

Postoperative corneal sensitivity was not remarkably changed after ReLEx smile surgery compared with FS-LASIK. This might be because ReLEx is a flapless procedure.     

Comparison of optical quality parameters and ocular aberrations after wavefront-guided laser in-situ keratomileusis versus wavefront-guided laser epithelial keratomileusis for myopia

Background

To compare optical quality, ocular scattering, and higher-order aberrations (HOAs) after laser in-situ keratomileusis (LASIK) versus laser epithelial keratomileusis (LASEK).

Methods

A total of 47 eyes from 47 participants who had undergone LASIK (group I) or LASEK (group II) procedure at least 6 months prior were enrolled. Ocular aberrations and modulation transfer function (MTF) values measured using iTrace, a ray-tracing type aberrometer, were compared to MTF (modulation transfer function) cut-off values, Strehl ratio, and objective indices of scattering obtained using the Objective Quality Analysis System II (OQAS II).

Results

There was no significant correlation between the postoperative optical quality parameters and the HOAs between both groups. In group I, the MTF cut-off value was significantly correlated with cylinder refraction (p?=?0.037), and the objective scattering index (OSI) was positively correlated with spherical equivalent (p?=?0.023). In group II, there was a statistically significant correlation between the OSI and achieved refractive correction (p?=?0.001). Regression analysis showed that the OSI was the most significant predictor of MTF cut-off values after refractive surgery. Additionally, MTF values measured by OQAS were significantly lower than those measured by iTrace without correlation.

Conclusion

Optical quality after refractive surgery may be influenced by not only ocular aberrations but also by scattering. Even though the accuracies of the machines used in this study to measure optical quality have yet to be proven, this study showed limited correlation among the values measured using the two different machines after refractive surgery. Therefore, for more generalized evaluation of visual function after refractive surgery, more advanced optical devices still need to be developed.     

Corneal biomechanical properties in 3 corneal transplantation techniques with a dynamic Scheimpflug analyzer

Purpose

To compare the corneal biomechanical properties of eyes that have undergone penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), and Descemet stripping automated endothelial keratoplasty (DSAEK).

Methods

This case–control study comprised 20 post-PK eyes, 14 post-DALK eyes, 15 post-DSAEK eyes, and 50 normal control eyes. A dynamic Scheimpflug analyzer (the Corvis ST) was used to evaluate the corneal biomechanical properties including deformation amplitude (DA) and radius at the highest concavity (R _hc).

Results

In post-PK eyes, the mean DA was 1.20 ± 0.13 mm, which was significantly higher than those of the control eyes (1.07 ± 0.09) and the post-DSAEK eyes (1.08 ± 0.12). The DA (1.18 ± 0.18) in the post-DALK eyes was significantly higher than in the control eyes. The R _hc in the post-PK (6.34 ± 0.37 mm), -DALK (6.04 ± 1.22), and -DSAEK (6.44 ± 0.58) eyes was significantly smaller than in the control eyes (7.57 ± 0.78).

Conclusions

The dynamic Scheimpflug analyzer provides a method to obtain new biomechanical information on the cornea such as the DA and R _hc, and these parameters differed among eyes that had undergone 3 different types of corneal surgery. Abnormalities in these parameters after the different corneal transplantation techniques may indicate larger deviations in the stress–strain reaction of the cornea and more uncertainty in the intraocular pressure measurements than in normal eyes.     

波前像差引导联合非球面LASIK治疗近视散光术后疗效观察

目的：观察波前像差引导联合非球面LASIK治疗近视散光眼的临床疗效。
　　方法：前瞻性研究。选取拟行LASIK手术治疗的近视散光眼患者45例62眼,随机分为两组,分别接受波前像差引导联合非球面LASIK与波前像差引导LASIK。观察术后6 mo两组安全性、有效性、预测性、全眼高阶像差及暗光下对比敏感度的差异。
　　结果：两种切削模式的安全性、有效性及预测性相似。术后6mo,两组各高阶像差均较术前增大,差异有统计学意义(P<0.01),波前像差引导联合非球面组总高阶像差及球差的增幅小于波前像差引导组,差异有统计学意义(P<0.05),两组术后彗差的增幅无统计学差异(P=0.657)。波前像差引导联合非球面组术后6 mo暗光下对比敏感度在各个空间频率均恢复至术前水平,差异无统计学意义(P>0.05);波前像差引导组除低空间频率外,其余空间频率恢复至术前水平,差异无统计学意义(P>0.05)。
　　结论：波前像差引导联合非球面LASIK较波前像差引导LASIK可更好地减少术后高阶像差的增加,改善暗光下对比敏感度。     

Topography-guided CATz versus conventional LASIK for myopia with the NIDEK EC-5000: A bilateral eye study

PURPOSE: To evaluate the difference in visual acuity, subjective night vision glare, and higher order aberrations in eyes with myopia with or without astigmatism operated with topography-guided customized corneal LASIK and conventional LASIK. METHODS: This contralateral study includes 46 eyes (23 patients) that underwent topography-guided corneal customized LASIK using the customized aspheric treatment zone (CATz) ablation profile in one eye and conventional LASIK using the NIDEK EC-5000 Advanced Vision Excimer laser system (NAVEX) in the other eye for myopia with or without astigmatism. Patients were masked to which eye underwent topography-guided CATz or conventional LASIK. Postoperative glare and root-mean-square (RMS) values for total higher order aberrations were measured at 1 and 3 months and compared between the two eyes. RESULTS: No significant difference was noted in uncorrected visual acuity between the two groups at 1 and 3 months postoperatively. Of all patients, 81% stated glare was higher in conventionally treated eyes than in the CATz-treated eyes at 1 and 3 months postoperatively. The RMS values for total coma (0.2385 vs 0.1522) and spherical aberration (0.2381 vs 0.1058) in conventionally treated and CATz-treated eyes were significantly higher in conventionally treated eyes (P=.029 and P=.004, respectively) at 3-month follow-up. CONCLUSIONS: Topography-guided corneal customized LASIK with the CATz profile gave better night vision quality as compared to conventional LASIK with expanded treatment zone. Better night vision quality was associated with less induced spherical aberrations and coma postoperatively in the CATz treatment group.     

The efficacy and safety of modified Snyder–Thompson posterior scleral reinforcement in extensive high myopia of Chinese children

Background

To observe the efficacy and safety of modified Snyder–Thompson posterior scleral reinforcement in extensive high myopia of Chinese children. We had a retrospective design, and included a control group of children with natural progression of high myopia.

Methods

This study included 64 eyes in 41 Chinese children with extensive high myopia who underwent modified Snyder–Thompson posterior scleral reinforcement surgery (PSR group), and 17 eyes in 11 age- and myopia-matched children who wore spectacles (control group). The mean follow-up was 4.99?±?1.3 years in the PSR group and 4.48?±?1.3 years in the control group. Axial length, spherical equivalent (SE), uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA) and fundus examinations were recorded before and after treatment, and complications were noted.

Results

The mean change in SE at the end of the follow-up period was 1.5?±?1.44 diopters (D) and 3.02?±?1.57D in the PSR and control groups respectively. These changes were equivalent to an increase in axial length of 1.27?±?0.54 mm and 2.05?±?0.91 mm respectively. The PSR group showed less myopic progression and less eye elongation (p?<?0.001). A notable increase in UCVA was only found in the PSR group (p?=?0.0001). The improvement in BCVA was significantly greater in the PSR group (p?=?0.0354). There were no serious complications of PSR surgery.

Conclusion

The modified Snyder–Thompson PSR surgery was effective and safe in controlling extensive high myopia of Chinese children.     

Subbasal nerve morphology, corneal sensation, and tear film evaluation after refractive femtosecond laser lenticule extraction

Background

The purpose of this study was to compare corneal subbasal nerve morphology, corneal sensation, and tear film parameters after femtosecond lenticule extraction (FLEX) and small-incision lenticule extraction (SMILE).

Methods

A prospective, randomized, single-masked, paired-eye design clinical trial of 35 patients treated for moderate to high myopia with FLEX in one eye and SMILE in the other. In both techniques, an intrastromal lenticule was cut by a femtosecond laser and manually extracted. In FLEX, a LASIK-like flap allowed removal of the lenticule, whereas in SMILE, it was removed through a small incision. In-vivo confocal microscopy was used to acquire images of the central corneal subbasal nerve plexus, from which nerve density, total nerve number, and nerve tortuosity were analyzed. Corneal sensation was measured using Cochet–Bonnet esthesiometry. A visual analog scale, tear osmolarity, non-invasive tear film break-up time (keratograph) tear meniscus height (anterior segment OCT), Schirmer's test, and fluorescein tear film break-up time were used to evaluate tear film and ocular surface symptoms. Patients were examined before and 6 months after surgery.

Results

There were no statistically significant differences in baseline parameters between FLEX and SMILE (p?>?0.050). With regard to changes from before to 6 months after surgery, mean reduction in subbasal nerve density was 14.22?±?6.24 mm/mm² in FLEX eyes, and 9.21?±?7.80 mm/mm² in SMILE eyes (p?<?0.05). The total number of nerves decreased more in FLEX eyes than in SMILE eyes (p?<?0.05). No change was found when comparing tortuosity (p?>?0.05). Corneal sensation was reduced with 0.38?±?0.49 cm in FLEX eyes, and 0.10?±?0.34 cm in SMILE eyes (p?<?0.01). No differences were found between FLEX and SMILE in tear film evaluation tests (p?>?0.05). Significantly more patients felt postoperative foreign body sensation in the FLEX eye within the first days after surgery, as compared to the SMILE eye.

Conclusions

Six months after surgery, the less invasive SMILE technique seemed better at sparing the central corneal nerves as compared to FLEX. Corneal sensation was only significantly reduced in FLEX eyes. There were no differences between FLEX and SMILE when comparing tear film evaluation tests 6 months after surgery.     

Comparison of myopic and nonmyopic disc hemorrhage in primary open-angle glaucoma

Purpose

To compare the topographic characteristics of myopic and nonmyopic disc hemorrhage (DH) in primary open-angle glaucoma.

Methods

Patients were assigned to the myopic DH group (spherical equivalent of ?1.0 diopters or less) or to the nonmyopic DH group (emmetropia and hyperopia). DH was classified as lamina cribrosa-, cup margin-, disc rim-, or peripapillary-type DH according to its proximal location. The DH types of the two groups were compared using Fisher's exact test. Multivariate logistic regression was used to evaluate the factors associated with myopia.

Results

Thirty-four eyes were assigned to the myopic DH group and 42 eyes to the nonmyopic DH group. A significantly higher proportion (32.4 %) of lamina cribrosa-type DH was found in the myopic DH group than in the nonmyopic DH group (4.8 %; P = 0.008). Eyes with lamina cribrosa-type DH were 12.59 times more likely to be myopic than were eyes with peripapillary-type DH (95 % CI: 1.22–129.53; P = 0.033).

Conclusions

Lamina cribrosa-type DH was significantly more common in myopic eyes than in nonmyopic eyes. This result suggests that the pathogenesis of DH may differ between myopic DH and nonmyopic DH.     

应用波前像差引导的LASEK治疗近视散光和低、高度近视

目的：对比在矫正低度近视,近视散光和高度近视时应用波前像差引导的激光上皮瓣下角膜磨镶术(LASEK)的安全性,有效性,可预测性,稳定性和并发症。

方法：该回顾性分析共纳入416眼,分为3组,低度近视组159眼,等值球镜-3.68±1.33D; 近视散光组161眼,等值球镜-5.99±2.24D,柱镜度2.41±1.07D; 高度近视组96眼,等值球镜-7.41±0.80D. 制瓣后,进行波前像差为基础的准分子激光削切术。在术后10d,2,6和12mo后评估其安全性,有效性,可预测性和稳定性。

结果：术后12mo,低度近视组等值球镜-0.36±0.31D,近视散光组0.15±0.41D,高度近视组0.58±0.68D。低度近视组中,裸眼视力为20/20的患者占90.60%,近视散光组78.90%,高度近视组67%。疗效指标在三组中分别为0.98, 1.04和0.92. 安全性指标分别为1.00, 1.07 和1.05。低度近视组有5眼(3.1%)最佳矫正视力提升1行,近视散光组有44眼(27.3%)提升1～3行,高度近视组18眼(19.2%)提升1～2行。低度近视组只有2例产生角膜雾状混浊。在疗效和安全性方面三组比较均无统计学差异。

结论：波前像差引导的激光上皮瓣下角膜磨镶术是治疗低度近视,近视散光和高度近视的一种有效安全的方法,而在治疗近视散光时其可预测性、有效性和安全性更佳。     

Comparison of visual and refractive results of Toric Implantable Collamer Lens with bioptics for myopic astigmatism

Purpose

To compare visual and refractive results of Toric Implantable Collamer Lens (TICL) and bioptics (ICL plus excimer corneal surgery) to treat myopic astigmatism.

Methods

Eighty-one eyes underwent TICL implantation and 83 eyes were treated with bioptics (corneal ablation was performed between 1.5 and 6 months after ICL implantation). Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction, adverse events, safety, and efficacy were evaluated 12 months postoperatively.

Results

At 12 months postoperatively, the mean spherical equivalent was ?0.15?±?0.36 diopters (D) in the TICL group and ?0.08?±?0.26 D in the bioptics group (p?=?0.099). Sixty-six (81.5 %) and 78 (94.0 %) eyes were within ±0.50 D for TICL and bioptics groups, respectively. The mean Snellen UDVA was not statistically different between both procedures (p?=?0.909); 53 (65.4 %) and 54 (65.1 %) eyes achieved at least 20/25 or better in TICL and bioptics groups, respectively. No eye had lost more than two lines of CDVA, and 32.1 % of eyes (26/81) in the TICL group and 57.8 % of eyes (48/83) in the bioptics group had better postoperative UDVA than preoperative CDVA (p?<?0.001). Safety was not statistically different between groups (p?=?0.464) while efficacy was significantly higher in the bioptics group (p?=?0.000). Two eyes with a TICL were treated to correct TICL decentration.

Conclusions

Bioptics showed slightly better outcomes in some clinical measures such as uncorrected visual acuity, efficacy, and refractive predictability. TICL implantation shows reliable results similar to bioptics. A single procedure with TICL implantation might be preferred, eliminating the inherent risks of laser treatments and the risks of a second surgical procedure.