Investigation of corneal biomechanics at moderate to high refractive errors

Purpose

Corneal hysteresis (CH) and corneal resistance factor (CRF) are corneal biomechanical parameters which were measured by ocular response analyzer (ORA). Aim of this study was to define the CH and CRF in high myopic and hyperopic patients and compare the results with emmetropic control group.

Methods

A total of 193 eyes of 100 healthy volunteers were included. Study groups were high myopic patients (n = 27) with spherical refractive errors (SRE) of greater than ?5.00D, high hyperopic patients (n = 20) with SRE of greater than +3.00D and controls (n = 53) with SRE between ± 1.00D. All subjects underwent IOP and corneal biomechanical evaluation with the ORA. Also Goldmann applanation tonometry (GAT), central corneal thickness (CCT), corneal curvature and axial length measurements were taken.

Results

Mean age of groups was 30.7 ± 6.9, 29.1 ± 7.7, 28.9 ± 5.6 years (p > 0.05). Among study groups except CRF and CCT, all parameters were significantly different between study groups. CH was lowest in the high myopic group and highest in the high hyperopia. In all groups, there were significant correlations between CH and CRF, CCT, SRE, SE (spherical equivalent), AL (axial length) and between CRF and CCT. GAT and IOPg (Goldmann-correlated intraocular pressure) measurements were significantly correlated with CCT (p < 0.05). One of the major findings was as the CH approaches 11.2 mmHg, IOPcc (corneal-compensated intraocular pressure) and IOPg get close to each other.

Conclusions

The results revealed that CRF is not affected by refractive errors and IOPcc is not affected by any other ocular parameter. The difference between IOPcc and IOPg was greatest in myopic group, and IOP (intraocular pressure) measurement in these patients deserves high suspicion.

     

Age-dependency of ocular parameters: a cross sectional study of young and elderly healthy subjects

Purpose

To investigate the effect of aging on ocular parameters, including intraocular pressure (IOP), measured with different tonometry methods in healthy young (HY) and healthy elderly (HE) subjects and to study the effect of corneal parameters on tonometry methods.

Methods

In this prospective, cross-sectional study, fifty eyes of 50 HY subjects (28 females, 22–31 years of age) and 43 eyes of 43 HE subjects (22 females, 64–79) were included. IOP was measured with four tonometry methods in a standardized order: ocular response analyser (ORA), dynamic contour tonometry (DCT), applanation resonance tonometry (ART) and Goldmann applanation tonometry (GAT). Other measurements included axial length (AL), central corneal thickness (CCT), corneal curvature (CC), anterior chamber volume (ACV), corneal hysteresis (CH) and corneal resistance factor (CRF).

Results

The mean IOP (HY/HE; mmHg?±?standard deviation (SD)) was 12.2?±?2.2/14.1?±?3.5 with GAT. IOP was significantly higher (difference?±?standard error) in HE compared to HY measured with an ORA (+3.1 mmHg?±?0.6), GAT (+1.9?±?0.6) and DCT (+1.6?±?0.6). No significant difference was found in IOP measured with ART. CH and ACV were significantly lower in HE compared to HY. There was no difference between the groups in CCT, CC, AL or CRF. No tonometry method was dependant on CCT or CC.

Conclusions

IOP measured with an ORA and via DCT and GAT was higher in HE compared to HY Swedish subjects, while IOP measured with ART did not differ between the groups. In these homogeneous groups, tonometry methods were independent of CCT and CC.

     

Evaluating internal and ocular residual astigmatism in Chinese myopic children

Purpose

To investigate the nature of internal astigmatism (IA) and ocular residual astigmatism (ORA) in Chinese myopic children and to identify factors that may influence IA and ORA.

Methods

A total of 206 eyes of 206 myopic children (97 boys and 109 girls; 10.95 ± 2.2 years) were enrolled in this cross sectional study. Total ocular astigmatism (TOA), anterior corneal astigmatism (ACA), posterior corneal astigmatism (PCA) and total corneal astigmatism (TCA) were measured directly using either a Hartmann–Shack wavefront sensor or a Pentacam. IA and ORA were calculated by Fourier vector analyses (the definitions of IA and ORA are: IA = TOA ? ACA ? PCA, ORA = TOA ? ACA). Spearman or Pearson correlation was adopted to detect multiple factors that may influence IA and ORA, which were then predicted by linear regressions. Modified compensation factors were applied to evaluate the inter-relationship between corneal astigmatism and ORA.

Results

While the mean values of IA and ORA were ?0.52 DC × 94.8° and ?0.63 DC × 93.0°, respectively, the percentage of ORA power over 1.00 D was as high as 28.64%. Full or under-compensation of ACA by ORA predominated in the enrolled subjects. The mean ORA J₀ and J₄₅ were ?0.311 ± 0.236 and ?0.032 ± 0.156 D, respectively, negatively correlated with the corresponding ACA components (J₀: r = ?0.276, J₄₅: r = ?0.616, p < 0.001). While age was not correlated with either IA or ORA (p > 0.1), the power of IA or ORA was correlated inversely with the axial length (IA: r = ?0.193, p = 0.005; ORA: r = ?0.169, p = 0.015) and positively with the spherical equivalent refraction (IA r = 0.195, p = 0.005; ORA r = 0.213, p = 0.002) and power of corneal astigmatism (IA-ACA: r = 0.302, IA-TCA: r = 0.368, ORA-ACA: r = 0.334, ORA-TCA: r = 0.293). Girls had larger IA powers than boys (0.741 ± 0.345 D vs 0.651 ± 0.340, p = 0.036).

Conclusions

Full or under-compensation of ACA by ORA is common in Chinese myopic children, and the compensation efficiency may decrease with age. Among Chinese children with myopia, a larger ORA is more prevalent with less myopia and greater corneal astigmatism.

     

Wound stability and surgically induced corneal astigmatism after transconjunctival single-plane sclerocorneal incision cataract surgery

Purpose

To compare intraocular pressure (IOP) immediately after cataract surgery, and surgically induced corneal astigmatism (SIA) and corneal shape changes between eyes with transconjunctival single-plane sclerocorneal incisions (TSSIs) and eyes with clear corneal incisions (CCIs).

Methods

Bilateral eyes of 64 patients undergoing phacoemulsification were randomized to undergo 2.4-mm temporal TSSI or CCI. IOP was measured preoperatively, and in the immediate postoperative periods. SIA was determined using vector analysis, and corneal shape changes and irregular astigmatism were evaluated using a videokeratography preoperatively, and in the early postoperative periods.

Results

Wound hydration was performed in 23 eyes (35.9 %) of the TSSI group and in 60 (93.8 %) of the CCI group (P < 0.0001). Mean IOP was significantly higher in the TSSI group than in the CCI group at 30, 60, and 120 min postoperatively (P ≤ 0.0179). SIA tended to be smaller in the TSSI group than the CCI group, but the difference was not significant. The higher order irregular astigmatism was smaller in the TSSI group than in the CCI group at 2 days (P = 0.0312). The videokeratography revealed a wound-related flattening postoperatively in both groups; this change disappeared within 4 weeks in the TSSI group, whereas it persisted until 12 weeks in the CCI group.

Conclusion

IOP was significantly higher immediately after TSSI than after CCI and required less wound hydration, suggesting better stability with TSSI. Higher order irregular astigmatism and wound-related corneal flattening were smaller after TSSI than after CCI in the early periods, suggesting that fewer corneal shape changes with TSSI.

     

Visual acuity and corneal higher-order aberrations after EX-PRESS or trabeculectomy,and the determination of associated factors that influence visual function

Purpose

This study investigated postoperative visual acuity and corneal higher-order aberrations following EX-PRESS or trabeculectomy.

Methods

Out of 56 eyes of 56 patients analyzed, 30 eyes were treated using trabeculectomy, while 26 eyes were treated with EX-PRESS. Visual acuity and corneal higher-order aberrations were analyzed in both groups before and at 2 weeks, 1, 2, and 3 months after the surgeries. Risk factors that could potentially influence corneal higher-order aberrations were evaluated.

Results

Significant reductions in the IOP were observed at 3 months after the surgery in both groups. Although a significant decrease in the visual acuity (logMAR) was observed at 2 weeks after the surgery in both groups, at 1 month after the surgeries, there were no significant differences found for the vision as compared to the baseline. At each study visit in the trabeculectomy group, significantly higher corneal higher-order aberrations compared to baseline were noted. In the EX-PRESS group, however, these aberrations were no longer significantly different from the baseline at month 2 (P = 0.36). Analysis of the risk factors indicated that hypotony could influence corneal higher-order aberrations after surgery.

Conclusions

Corneal higher-order aberrations were significantly increased at 1 month after EX-PRESS treatment, with levels returning to baseline by 2 months. After trabeculectomy, however, corneal higher-order aberrations remained significantly increased at 3 months after the procedure.

     

Evaluation of the effect of daily activities on intraocular pressure in healthy people: is the 20 mmHg border safe?

Purpose

The aim of this prospective study was to evaluate the intraocular pressure (IOP) variations during daily activities such as reading, speaking and carrying in regard to investigating whether an elevation or decrease exists.

Subjects and methods

Forty-four eyes of 44 healthy subjects were evaluated. The IOP was measured in relaxation and after reading, speaking and carrying a shopping bag for 5 min on different days, respectively. The subjects rested for 15 min between the activities. Mean initial IOP levels were compared with mean IOP levels after reading, speaking and carrying a shopping bag with paired t test. A p value of 0.05 was considered as statistically significant.

Results

We observed no changes in mean IOP after reading (p = 0.188). Mean IOP was increased after speaking and carrying compared with mean basic IOP (p = 0.001 and p = 0.001, very significant, respectively). The mean IOP began to decrease 15 min after speaking and carrying and came back to the baseline values one hour later.

Conclusions

The IOP is not stable during daily activities. Simple actions such as carrying or speaking have an increasing effect on IOP. This should be taken into consideration in glaucoma patients during control measurements, especially in patients in whom the IOP was near to the 20 mmHg border.

     

Measurement repeatability of the dynamic Scheimpflug analyzer

Purpose

To evaluate the repeatability of corneal deformation parameters measured using a dynamic Scheimpflug analyzer and the impact of baseline clinical factors on the repeatability of each parameter.

Study design

Retrospective, cross-sectional study.

Methods

Forty-eight eyes (48 healthy subjects; mean age, 49.0 ± 19.5 years) underwent repeated examinations with the Scheimpflug analyzer to evaluate the test–retest variability. The intraclass correlation coefficient (ICC) and repeatability coefficient as indicators of variability were computed for 35 parameters measured with the Scheimpflug analyzer. The associations between the magnitude of the test–retest variability and baseline factors, such as age, axial length (AL), intraocular pressure (IOP), and central corneal thickness (CCT), were analyzed.

Results

The test–retest repeatability was excellent for 22 (62.9%) of 35 parameters (ICC ≥ 0.75), good for seven (20%), (ICC ≥ 0.6), fair for four (11.4%), (ICC ≥ 0.4), and poor for two (5.7%) parameters (ICC < 0.4). Age was associated positively with the magnitude of variability in 13 (37.1%) parameters; measurement variability was affected significantly by AL (5 parameters, 14.3%) and CCT (7 parameters, 20%) but, except for one parameter not by IOP.

Conclusion

Most parameters of the dynamic Scheimpflug analyzer showed favorable measurement reliability in healthy subjects. However, six parameters showed poor-to-fair repeatability. Age, AL, and CCT significantly affected the repeatability of several parameters. These results should be considered when clinicians use this device in clinical practice.

     

Safety and effectiveness of gold glaucoma micro shunt for reducing intraocular pressure in Japanese patients with open angle glaucoma

Purpose

To assess the safety and effectiveness of the SOLX gold shunt (GS) in reducing intraocular pressure (IOP) in Japanese patients with open angle glaucoma (OAG).

Methods

24 eyes of 24 subjects [mean age of 68.9 ± 12.7 years; 13 (54%) women; 16 (67%) POAG, 7 (29%) pseudoexfoliation glaucoma, and 1 (4%) steroid response glaucoma] were implanted with the GS either with or without cataract surgery. Best-corrected visual acuity (BCVA), IOP, corneal endothelial cell density (CECD), anterior chamber (AC) flare, surgical complications, and required interventions were monitored at baseline, and 1 day, 1 week, 1, 3 and 6 months, and 1 year postoperatively.

Results

Baseline IOP of 21.3 ± 4.1 mmHg and glaucoma medications of 3.5 ± 1.0 were significantly reduced at every follow-up visit. At 1 year postoperatively, IOP was 16.4 ± 5.8 mmHg (23% reduction from baseline, p < 0.0001) with use of 2.1 ± 1.1 medications (40% reduction from baseline, p = 0.0002). Intraoperative hyphema occurred in 5 (21%) eyes. Transient bleb formation occurred in 20 (83%) eyes, and AC cell was reported in 17 (71%) eyes. Inflammation-related complications such as posterior and anterior synechiae, or iritis/keratic precipitates tended to occur during late postoperative periods. At 1 year, BCVA was unchanged or improved in 23 (96%) eyes. AC flare was elevated at 1 week postoperatively and later. CECD declined at 3 months and 1 year postoperatively.

Conclusions

The GS is effective in reducing IOP in Japanese patients with OAG. Chronic inflammation in AC might be associated with late onset complications.

     

Performing corneal crosslinking under local anaesthesia in patients with Down syndrome

Purpose

To report on the ability to perform corneal crosslinking (CXL) under local anaesthesia for the treatment of keratoconus in patients with Down syndrome.

Methods

Nine eyes of seven patients with both keratoconus and Down syndrome were scheduled for an epithelium-off CXL procedure under local anaesthesia. Exclusion criteria were a corneal thickness under 400 µm and the presence of corneal scars. A standardized clinical decision tool was used to estimate patient cooperation and the likelihood for a successful procedure under local rather than general anaesthesia.

Results

In seven eyes, the CXL was completed successfully. The treatment was aborted in two eyes due to insufficient corneal thickness (<400 µm) prior to ultraviolet-A irradiation, even after employing hypoosmolar riboflavin. No adverse events occurred post-operatively, except for one case of delayed epithelial healing (23 days).

Conclusions

With a proper patient selection, CXL under local anaesthesia can be achieved in patients with Down syndrome.

     

The effect of the extent of the incision in the Schlemm canal on the surgical outcomes of suture trabeculotomy for open-angle glaucoma

Purpose

To examine the relationship between the extent of the incision in the Schlemm canal during suture trabeculotomy (S-LOT) for open-angle glaucoma and the associated reduction in intraocular pressure (IOP).

Methods

Forty-eight consecutive eyes (primary open-angle glaucoma: 28; exfoliation glaucoma: 20) scheduled to undergo S-LOT were studied. A 320-degree opening in the Schlemm canal was planned when total circumferential cannulation had been achieved, and the remaining 40-degree region under the scleral flap was not incised. When the cannulation was incomplete, the canal was incised up to the point reached by the cannula, and the extent of the incision was measured. Logistic regression analysis was performed to identify potential predictors of surgical success (IOP ≤ 15 mmHg).

Results

A 320-degree incision was achieved in 23 eyes, and the mean extent of the incision was 275 ± 52.3°. The mean IOP fell from 34.0 ± 8.8 mmHg at baseline to 14.5 ± 4.0 mmHg at 1 year postoperatively (P < 0.0001). An IOP reduction of ≥30% was achieved in 46 eyes. Simple correlation analysis indicated that the extent of the incision in degrees did not correlate with IOP or with the reduction in IOP at 1 year postoperatively (P = 0.7665 and 0.693, respectively). Lower preoperative IOP values and concomitant cataract extraction were found to be associated with surgical success.

Conclusions

The extent of the incision in the Schlemm canal during S-LOT does not correlate with postoperative reduction in IOP.

     

Effectiveness and safety of combined cataract surgery and microhook ab interno trabeculotomy in Japanese eyes with glaucoma: report of an initial case series

Purpose

To report the early postoperative results and safety profile of ab interno microhook trabeculotomy (μLOT) combined with cataract surgery.

Patients and methods

This retrospective observational case series included 68 consecutive glaucomatous eyes of 23 Japanese men and 25 Japanese women [mean (SD) age, 76.0 ± 8.5 years] who underwent μLOT for intraocular pressure (IOP) and visually relevant cataracts. The LOT site/extent, perioperative complications, and complication treatments were collected from the medical and surgical records. The preoperative and postoperative IOP, numbers of antiglaucoma medications, logarithm of the minimum angle of resolution visual acuity (VA), anterior chamber (AC) flare, and corneal endothelial cell density (CECD) were compared.

Results

After small incisional cataract surgery, the trabecular meshwork was incised in the nasal (6 eyes, 3.6 ± 0.5 clock hours), temporal (6 eyes, 3.8 ± 0.8 clock hours), or both nasal and temporal (56 eyes, 6.5 ± 0.6 clock hours) angles. The mean preoperative IOP (16.4 ± 2.9 mmHg) and number of antiglaucoma medications (2.4 ± 1.2) decreased significantly (P < 0.0001 and P = 0.0039, respectively) to 11.8 ± 4.5 and 2.1 ± 1.0 mmHg at 9.5 months postoperatively. Compared with the preoperative conditions, the final VA improved (P = 0.0002), the AC flare increased by 6.3 pc/ms (P = 0.0157), and the CECD decreased by 6% (P = 0.0005). Hyphema with niveau formation (28 eyes, 41%) and hyphema washout (6 eyes, 9%) were the most common postoperative complication and intervention, respectively. At the final visit, 54 eyes (79%) had achieved successful IOP control of 15 mmHg or less and IOP reduction of 15% or greater.

Conclusion

Combined μLOT and cataract surgery improves IOP and VA during the early postoperative period in patients with glaucoma and cataract.

     

Corneal topographic alterations after selective laser trabeculoplasty

Purpose

To investigate the presence of corneal alterations in the long term among patients with primary open-angle glaucoma (POAG) after a single session of selective laser trabeculoplasty (SLT) treatment.

Materials and methods

The files of the POAG patients who had been treated with SLT were evaluated retrospectively. The Pretreatment Scheimpflug corneal topographic (SCT) findings were then compared with the post-treatment findings.

Results

The files of 33 patients were eligible. The changes in central corneal thickness, thinnest point of cornea, and posterior corneal asphericity at 5 and 8 mm were statistically significant (p = 0.03, 0.01, 0.02, and 0.04 respectively). On the other hand, the simulated K, anterior 3 mm K, anterior 5 mm K, posterior 3 mm K, posterior 5 mm K, anterior asphericity at 3 mm, posterior asphericity at 3 mm, and Zernike values did not change significantly following the treatment (p = 0.19, 0.08, 0.1, 0.3, 0.2, 0.75, 0.09, and 0.3 respectively).

Conclusion

SLT can slightly alter pretreatment SCT findings in 3–6 months. Clinicians should wait for at least 6 months after SLT before performing any subsequent surgeries that depend on corneal parameters.

     

Clinical utility of femtosecond laser-assisted astigmatic keratotomy after cataract surgery

Purpose

To examine the clinical utility of femtosecond laser-assisted astigmatic keratotomy (FSL-AK) for eyes after cataract surgery.

Methods

Eight eyes of 6 patients with an intraocular lens and corneal astigmatism of 2.0 diopters (D) or more underwent FSL-AK. The mean preoperative manifest cylindrical refraction was 2.88 ± 0.64 D and the mean corneal astigmatism was 2.84 ± 0.83 D. Paired symmetrical arcuate incisions were created with the same settings, except for the incision depth. Uncorrected distance visual acuity (UDVA), manifest cylindrical power, and surgically induced astigmatism (SIA) were measured at 1 day, 1 week, and 1 month postoperatively. Fourier analysis of corneal topography and incision depths measured with anterior-segment optical coherence tomography were evaluated 1 month postoperatively.

Results

In all eyes, the UDVA improved at 1 week and 1 month postoperatively, and the manifest cylinder also decreased postoperatively, while the SIA showed overcorrections in 6 eyes. Fourier analysis showed decreases in spherical and regular astigmatic components and increases in higher-order irregularity. The mean incision depth was measured as 60 µm deeper than the intended depth.

Conclusion

The FSL-AK effectively reduced corneal astigmatism and improved the UDVA, although it was demonstrated that the deeper incisions led to overcorrection.

     

Effect of glaucoma implant surgery on intraocular pressure reduction,flare count,anterior chamber depth,and corneal endothelium in primary open-angle glaucoma

Purpose

To evaluate the effect of filtering surgery using the EX-PRESS device on intraocular pressure (IOP), flare count, anterior chamber (AC) depth, and the corneal endothelium in primary open-angle glaucoma (POAG), including normal-tension glaucoma (NTG).

Patients and methods

The study comprised 63 consecutive patients with POAG or NTG. They underwent complete ophthalmologic examinations, including measurement of visual acuity (VA), IOP, flare count, AC depth, and cell density of the corneal endothelium (CE). Two outcomes were used for surgical success: outcome 1 was defined as a ≥20% reduction in the IOP from the preoperative value, with an IOP ≥ 5 mmHg but ≤18 mmHg, and outcome 2 was defined as a ≥20% reduction in the IOP, with an IOP ≥ 5 mmHg but ≤15 mmHg.

Results

The IOP significantly decreased from 17.7 preoperatively to 12.4 mmHg postoperatively (P < 0.0001). The success rates for outcome 1 at 24 months were 81.3 and 46.7% for POAG and NTG, respectively (P = 0.0065); the corresponding success rates for outcome 2 were 79.4 and 46.7% (P = 0.0120). The flare count significantly increased on postoperative day 1 (P = 0.0002) but recovered to insignificant levels by day 3 (P = 0.0686). A transient decrease in AC depth was observed by 4 weeks after surgery (P = 0.0017). The CE changed from 2529 preoperatively to 2428/mm² at 24 months (P = 0.0089).

Conclusion

The advantage of filtering surgery using the EX-PRESS device includes reduced inflammation, and the disadvantages include loss of the CE and reduced effectiveness of NTG.

     

Isoflurane and ketamine:xylazine differentially affect intraocular pressure-associated scotopic threshold responses in Sprague-Dawley rats

Purpose

Amplitudes of electroretinograms (ERG) are enhanced during acute, moderate elevation of intraocular pressure (IOP) in rats anaesthetised with isoflurane. As anaesthetics alone are known to affect ERG amplitudes, the present study compares the effects of inhalant isoflurane and injected ketamine:xylazine on the scotopic threshold response (STR) in rats with moderate IOP elevation.

Methods

Isoflurane-anaesthetised (n = 9) and ketamine:xylazine-anaesthetised (n = 6) rats underwent acute unilateral IOP elevation using a vascular loop anterior to the equator of the right eye. STRs to a luminance series (subthreshold to ?3.04 log scotopic cd s/m²) were recorded from each eye of Sprague-Dawley rats before, during, and after IOP elevation.

Results

Positive STR (pSTR) amplitudes for all conditions were significantly smaller (p = 0.0001) for isoflurane- than for ketamine:xylazine-anaesthetised rats. In addition, ketamine:xylazine was associated with a progressive increase in pSTR amplitudes over time (p = 0.0028). IOP elevation was associated with an increase in pSTR amplitude (both anaesthetics p < 0.0001). The absolute interocular differences in IOP-associated enhancement of pSTR amplitudes for ketamine:xylazine and isoflurane were similar (66.3 ± 35.5 vs. 54.2 ± 24.1 µV, respectively). However, the fold increase in amplitude during IOP elevation was significantly higher in the isoflurane- than in the ketamine:xylazine-anaesthetised rats (16.8 ± 29.7x vs. 2.1 ± 2.7x, respectively, p = 0.0004).

Conclusions

The anaesthetics differentially affect the STRs in the rat model with markedly reduced amplitudes with isoflurane compared to ketamine:xylazine. However, the IOP-associated enhancement is of similar absolute magnitude for the two anaesthetics, suggesting that IOP stress and anaesthetic effects operate on separate retinal mechanisms.

     

Corneal endothelial changes following a single session of selective laser trabeculoplasty for pseudoexfoliative glaucoma

Purpose

To evaluate corneal endothelial cell parameters after a single session of selective laser trabeculoplasty (SLT) in pseudoexfoliative glaucoma (PEG) patients.

Methods

Corneal endothelial cell parameters of 18 PEG patients were compared with 18 healthy subjects following SLT treatment. All patients underwent SLT treatment to 180 degrees of inferior trabecular meshwork. Corneal measurements were performed using specular microscopy (Noncon Robo SP8000, Konan Medical, Hyogo, Japan). Endothelial cell density (ECD), hexagonal cell ratio (HEX), coefficient of variation (CV) of the corneal endothelial cell layer and central corneal thickness of the patients were measured at each visit.

Results

There was a statistically significant decrease in ECD (p = 0.004) and a statistically significant increase in CV (p = 0.041) at superior cornea 1 week after SLT. They returned to pre-SLT values at 1 month. One hour post-SLT HEX of inferior cornea was statistically significantly reduced (p = 0.01). At central cornea, there was a significant increase in HEX after 1 week (p = 0.001). Post-SLT IOP showed a significant positive correlation with CV and significant negative correlation with HEX at superior and inferior cornea. There was no correlation between total laser energy used and endothelial cell parameters.

Conclusion

Effect of a single session of SLT on corneal endothelium of PEG patients appears to be transient, and superior cornea was more affected than central and inferior cornea. All parameters returned to pre-SLT values at 1 month after treatment.

     

Inhibitory effects of bevacizumab on angiogenesis and corneal neovascularization

Background

To evaluate the inhibitory effects of bevacizumab (Avastin®) on angiogenesis using cultured human umbilical vein endothelial cells (HUVECs) in vitro and on corneal neovascularization by subconjunctival injection of bevacizumab in vivo.

Methods

After the HUVECs were exposed to different concentrations of bevacizumab stimulated with VEGF (10 ng/ml) for 2, 6, and 24 hours, cellular-activity-like proliferation, migration and tube formation were assessed. Subconjunctival injection of bevacizumab (2.5 mg/0.1 ml) was performed after corneal chemical burn injury. Then the cornea was evaluated by biomicroscopy, fluorescein angiography, and light microscopy.

Results

The inhibitory effects of bevacizumab on VEGF-induced HUVECs proliferation showed a dose-dependent response for 2 and 6 hours, but all groups were effectively inhibited regardless of the concentration of bevacizumab for 24 hours. The inhibitory effects of bevacizumab on the migration of VEGF-induced HUVECs showed a time- and dose-dependent response. The inhibitory effects of bevacizumab on VEGF-induced HUVECs tube formation showed a dose-dependent response only for 24 hours. On days 3 and 8 after the subconjunctival injection, bevacizumab-treated eyes showed less neovascular growth than BSS-treated eyes in biomicroscopic, fluorescein angiographic, and light microscopic findings in vivo.

Conclusions

Bevacizumab effectively inhibits angiogenesis and corneal neovascularization, and could be used as a inhibitor of corneal neovascularization in the future.

     

Corneal crosslinking for keratoconus in Japanese populations: one year outcomes and a comparison between conventional and accelerated procedures

Purpose

We retrospectively investigated the efficacy of corneal crosslinking (CXL) on progressive keratoconus in a Japanese population and compared the outcomes of conventional and accelerated CXL.

Study design

A retrospective cohort study

Methods

A total of 108 consecutive eyes in 95 patients (75 men; 21.9 ± 6.2 years) with progressive keratoconus were enrolled. The epithelium was ablated in all eyes. After presoaking the corneal stroma in riboflavin, UV-A was irradiated at 3.0 mW/cm² (conventional CXL) for 30 min on 23 eyes and 18.0 mW/cm² for 5 min (accelerated CXL) on 85 eyes. Best spectacle-corrected visual acuity (BSCVA), manifest refraction, keratometric value, corneal thickness, corneal endothelial cell density (ECD), intraocular pressure, and complications were evaluated at 1, 3, 6, and 12 months after the procedure.

Results

BSCVA, manifest refraction, ECD, and corneal thickness did not change significantly after both procedures. The keratometric value was significantly decreased from the preoperative value at 12 months (p < 0.001). Progression to more than 1.0 D after CXL was observed in 10 eyes (9.3%). The ΔKmax was negatively associated with preoperative Kmax (p < 0.001) and positively associated with preoperative thinnest corneal thickness (p < 0.001). Both treatment modules showed no significant difference in all parameters.

Conclusion

CXL was as effective in treating keratoconus in Japanese patients as in individuals of other ethnicities. Overall, CXL could be performed using either the conventional or accelerated approach to halt the progression of keratoconus in Japanese populations.

     

Alterations in contact lens fitting parameters following cross-linking in keratoconus patients of Indian ethnicity

Background

Most studies have either excluded patients using contact lens or not taken their effect while analyzing post-collagen cross-linkage (CXL) changes. This study aims to study impact of CXL on lens fit in both quantitative and qualitative manner.

Objective

To evaluate changes in CL fit post-CXL and to correlate these changes with alterations in corneal topographic parameters.

Study design

Prospective intervention study on 20 keratoconic eyes of 14 patients (age > 18 years), with mean follow-up of 6 months.

Methods

Preoperative evaluation included UCVA, BCVA, corneal topography, AS-OCT and contact lens fit. Patients were evaluated at 2 weeks, 1, 3, 4 and 6 months post-CXL; contact lens trial with standard rigid gas permeable (RGP) lens performed at 3 and 6 months.

Main outcome measure

Changes in objective and subjective parameters of lens fit.

Results

Over 6-month follow-up post-CXL, improvement in visual acuity by one Snellen line, both UCVA and BCVA, and decrease in flat/mean/apical K by 0.8 D, 0.8 D and 1.3 D, respectively, resulted in significant improvement in RGPCL fit. Almost 20% increase in near-ideal fit, 100% acceptable fit, 65% improved subjective comfort with 8 h/day increase in duration of comfortable CL wear were observed.

Conclusion

Despite no statistically significant change in objective parameters of lens fit, a tendency for flatter lens fit along with contact lens induced further flattening of the ectatic cornea which resulted in marked improvement in both objective and subjective contact lens fit.

     

“Double scleral tunnel in tandem” technique for glaucoma drainage tube implants

Purpose

To describe a new technique of Ahmed glaucoma valve implantation in patients with refractory glaucoma and present the long-term results.

Methods

Twenty-eight eyes of 28 patients with refractory glaucoma participated in the study. “Double scleral tunnel in tandem” technique was used for glaucoma valve implantation in all patients. The technique consists of the formation of two scleral tunnels in tandem so as to completely cover the extraocular part of valve’s tube and facilitate a parallel to the iris placement of the intraocular part of the tube.

Results

Postoperative hypotony developed in two (7.1%) cases which resolved within 3 days in all cases. One (3.6%) eye manifested postoperative hyphema that resolved without complications within a week, and two (7.1%) cases presented with exposure of the tube. The average highest postoperative intraocular pressure (IOP) during the follow-up period was 19 mmHg (range 8–38 mmHg) without medications, and the average IOP at the last follow-up visit was 14.5 mmHg (range 8–22 mmHg). Additional treatment for IOP control was necessary in 11 (39.3%) cases. The average follow-up period was 60 months.

Conclusion

This novel technique was found to be easy to master, effective and with low cost and rate of complications.