Corneal and Scleral Problems Caused by Skin-Lightening Creams.

PURPOSE: To present a case series of patients with corneal and scleral changes associated with the use of skin-lightening creams. This is the first report of corneal changes with these widely available creams. METHODS: Three patients of West African origin presented with strikingly similar skin, corneal, and scleral changes and were found to have all been using skin-lightening creams containing hydroquinone. Histopathology was obtained for 1 patient. RESULTS: Three patients were referred to the corneal clinics of 2 hospitals with corneal changes and a history of blurred vision for 1 to 3 years. There was a 60-year-old woman from Nigeria and a 68-year-old woman and a 73-year-old man both from Ghana. All 3 had been using skin-lightening lotions containing hydroquinone on their faces for between 3 and 15 years and had black-blue facial pigmentation of exogenous ochronosis, a recognized complication of these creams. Their corneas all had horizontal striae radiating across the posterior corneas with scleral thinning and plaques. Linear brown epithelial pigmentation was observed within the lower third of the corneas. Biopsy of the sclera in 1 patient showed ochronosis. CONCLUSIONS: We present previously unreported eye changes associated with the use of skin-lightening creams containing hydroquinone, with a triad of signs: posterior corneal striae radiating from 3 o'clock to 9 o'clock, thinning and plaques in the sclera, and a normal endothelial cell count. Similar pathological changes are seen in exogenous ochronosis, a recognized skin complication of hydroquinone, are seen in the sclera.

Cytomegalovirus infection is not a major cause of corneal graft failure in the United Kingdom.

BACKGROUND: Cytomegalovirus (CMV) endotheliitis is a significant cause for acute corneal allograft rejection in East Asian populations, where there is a high CMV seroprevalence. To determine how frequently CMV is associated with corneal graft failure in the UK, we looked for the presence of CMV DNA in grafts that had failed and had been removed at repeat keratoplasty. We also looked for CMV DNA in corneal rims discarded after corneal transplantation. METHODS: In this retrospective study, we identified 54 cases of corneal graft failure following endothelial rejection and 38 control grafts that had failed without a history of endothelial rejection. For these groups archived formalin-fixed paraffin-embedded (FFPE) tissue samples were retrieved. We also prospectively examined 80 non-fixed cornea rims following transplantation surgery. In all samples nested quantitative PCR was used to identify CMV, herpes simplex virus (HSV) and varicella zoster virus (VZV) DNA. We also used in situ hybridisation to examine for CMV DNA in the FFPE samples. RESULTS: No CMV or VZV DNA was detected in any of the archived case or control FFPE tissues. One corneal rim from the control group was positive for HSV. In situ hybridisation for CMV was negative for CMV in all FFPE samples. No CMV, VZV or HSV DNA was detected in the donor corneal rim samples. CONCLUSION: CMV DNA was not identified in excised failed corneal tissue or from tissue prior to transplantation. We infer that CMV infection is not a significant factor risk for corneal graft failure in the United Kingdom.

Ex-vivo ocular surface stem cell therapies: current techniques, applications, hurdles and future directions.

Engineered tissue derived from ocular surface stem cells (SCs) are a cutting edge biotechnology for repair and restoration of severely damaged eyes as a result of ocular surface dysfunction because of SC failure. Ex-vivo SC expansion techniques have advanced significantly since the first patients were treated in the late 1990s. The techniques and clinical reports reviewed here highlight the evolution and successes of these techniques, while also revealing gaps in our understanding of ocular surface and SC biology that drives further research and development in this field. Although hurdles still remain before stem-cell-based therapies are more widely available for patients with devastating ocular surface disease, recent discoveries in the field of mesenchymal SCs and the potential of induced pluripotent SCs heralds a promising future for clinicians and our patients.

Effect of different femtosecond laser-firing patterns on collagen disruption during refractive lenticule extraction.

PURPOSE: To evaluate the changes in corneal collagen architecture subjected to different laser-firing patterns during refractive lenticule extraction. SETTING: Singapore Eye Research Institute, Singapore. DESIGN: Experimental study. METHODS: Refractive lenticule extraction was performed in rabbits without lenticule removal. Rabbits were divided into 4 groups that had incisions in the following firing patterns: (A) from periphery in (lenticule's posterior surface) and from center out (lenticule's anterior surface); (B) from center out and from center out; (C) from periphery in and from periphery in; and (D) from center out and from periphery in. The corneas were collected 18 hours postoperatively and were subjected to immunofluorescent staining of fibronectin, CD11b, and collagen type I. Ultrastructural analysis was performed using transmission electron microscopy (TEM). RESULTS: Refractive lenticule extraction-treated corneas showed no significant difference in fibronectin and CD11b expression. Similar expression patterns of collagen type I were observed in corneas that had femtosecond firing patterns A, B, and C; however, a discontinuous and relatively more intense staining pattern along the anterior plane of the lenticule was detected in corneas treated with pattern D. The TEM also showed a more disrupted collagen arrangement along the anterior incision site in pattern D-treated corneas. CONCLUSIONS: Differential laser firing patterns during refractive lenticule extraction resulted in different levels of collagen derangement along the anterior plane of the lenticule, with pattern D showing the most disrupted surface. Such disruption in the collagen architecture might affect postoperative visual recovery and refractive outcomes. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Refractive lenticule re-implantation after myopic ReLEx: a feasibility study of stromal restoration after refractive surgery in a rabbit model.

PURPOSE: To investigate the potential of refractive lenticule (RL) storage and re-implantation in vivo as a method for reversing RL extraction (ReLEx) and restoring corneal stromal volume. METHODS: ReLEx [-6.00 diopter (D) correction] was performed on six New Zealand White rabbits in one eye. Each extracted RL was tagged and orientated before storage at -80°C for 28 days. Each RL was then re-implanted autologously in the correct orientation after flap relifting. All animals were monitored for 28 days before being euthanized for immunohistochemical analysis. Unoperated fellow eyes were used as controls. All animals had regular pre- and postoperative slit lamp photography, in vivo confocal microscopy, anterior segment optical coherence tomography (AS-OCT), keratometry, and topography. RESULTS: No intra-operative complications occurred and RL re-implantation was performed without complication. A mild intrastromal haziness was noted on day 3 after re-implantation (corneal haze grade: 2.20 ± 0.45), but corneas were clear on day 28 (0.20 ± 0.27). RL re-implantation restored central corneal thickness, and keratometric and topographic indices to near pre-operative values. Wound healing processes, marked by fibronectin and tenascin, and a few inflammatory cells were present along the re-implanted lenticular interfaces. No myofibroblasts formation, and Ki67- and TUNEL-positive cells were observed in the corneal stroma on postoperative day 28. CONCLUSIONS: RL storage and re-implantation is a feasible technique for restoring stromal volume after myopic ReLEx, and may provide a method for restoring tissue in ectatic corneas, or provide an opportunity for further refractive surgery and presbyopic treatment.

Manual suction versus femtosecond laser trephination for penetrating keratoplasty: intraocular pressure, endothelial cell damage, incision geometry, and wound healing responses.

PURPOSE: To measure real-time intraocular pressure (IOP) during trephination with a manual suction trephine (MST) and the femtosecond laser (FSL), and to assess endothelial cell damage, incision geometry, and wound healing response with these procedures. METHODS: IOP was monitored with an intracameral sensor. Eight rabbits underwent manual suction trephination. Eight rabbits had FSL trephination (FSL-T). Slit lamp photography, confocal microscopy, and anterior segment optical coherence tomography (AS-OCT) were performed at baseline and postoperatively. Animals were sacrificed at 4 hours and 3 days. Tissue was examined with scanning electron microscopy (SEM) and immunohistochemistry for an array of wound-healing markers. Separately, 6 human corneas had MST (3) and FSL-T (3). Incision geometry was imaged with high resolution Optovue AS-OCT. RESULTS: The average IOP during MST and FSL-T was similar (37 mm Hg). There was wider IOP fluctuation during the MST cutting phase (60 mm Hg maximum). There were 1-2 rows of endothelial loss on either side of the incision for FSL-T and 2-5 rows deep for MST. Immune cell responses at 4 hours (CD11b) were comparable, greater apoptosis with FSL-T (TUNEL) occurred at 4 hours, and there was increased keratocyte proliferation at 3 days (Ki67) with FSL-T. There was significantly greater undercutting of the cornea with MST (46.86 degrees versus 16.72 degrees). CONCLUSIONS: There is more IOP variation during MST. Average IOP is 37 mm Hg for both techniques. More endothelial damage and undercutting of the cornea occurs with MST. The wound healing response to FSL-T appears greater at 3 days.

Theoretical, experimental, and optical coherence tomography (OCT) studies of graft apposition and adhesion in Descemets stripping automated endothelial keratoplasty (DSAEK).

PURPOSE: To investigate the effects of adhesion promoting surgical adjuncts in Descemets stripping automated endothelial keratoplasty (DSAEK). The effects of air-fill pressure, duration, use of venting incisions and stromal roughening on fluid dispersion, and donor adhesion strength were examined in theoretical, optical coherence tomography (OCT), and strain gauge models of DSAEK. METHODS: OCT analysis: DSAEK modeled using a microkeratome prepared lenticule inserted under a "recipient" corneo-scleral rim mounted on an artificial anterior chamber. Pressure of 18 mm Hg (n = 6) or 60 mm Hg (n = 6) was applied. The area of interface fluid was measured sequentially. The area of interface fluid before and after opening of venting incisions was measured (n = 6). Adhesion experiments: Direct measurement of adhesion force using a universal testing machine was performed. Peak adhesion after compression at 60 mm Hg/8 minutes, 60 mm Hg/1 minutes, 18 mm Hg/8 minutes, and 18 mm Hg/1 minutes (n = 8 each group) was measured. Subsequently, adhesion after complete removal of interface fluid and after stromal roughening was measured in separate samples (n = 12). RESULTS: Interface fluid diminishes with time during tamponade at both low and high pressures (P < 0.0001). Pressure had no effect on amount or rate of fluid dispersion. Venting incisions eliminated interface fluid in all samples when opened sufficiently. Adhesion is independent of anterior chamber air tamponade pressure (P = 0.38). Complete removal of interface fluid increases average adhesion (16.0 mN vs. 7.8 mN, P = 0.0001). Roughening of the host stroma increased adhesion (13.8 mN vs. 9.8 mN, P = 0.0034). CONCLUSIONS: Venting incisions and stromal roughening aid adhesion in DSAEK. Sustained high-pressure anterior chamber air tamponade has no demonstrable effect on measured fluid dispersion or adhesion strength.

Femtosecond lenticule extraction (FLEx): clinical results, interface evaluation, and intraocular pressure variation.

PURPOSE: To characterize the clinical profile of femtosecond lenticule extraction (FLEx) correlated with ultrastructural analysis of the corneal interface and in vivo real-time intraocular pressure (IOP). METHODS: Prospective clinical case series with experimental studies; consecutive patients underwent FLEx at a single tertiary center over 10 months with postsurgical follow-up of 3 months. The patients were divided into three groups according to spherical equivalence (SE) (A, < -5.0 diopters [D]; B, ≥ -5.00 D and < -9.00 D; and C, ≥ -9.0 D). Twelve human cadaveric eyes analyzed using scanning electron microscopy after receiving FLEx; 40 rabbit eyes received FLEx with in vivo IOP measurements. The main outcome measures were refractive outcomes from study subjects; with corneal interface and IOP in experimental studies. RESULTS: Thirty-three subjects (22 females, 66.7%) underwent FLEx in both eyes (66 eyes). Mean age was 32 years (range, 21 to 46 years). Preoperative mean SE was -5.77 ± 2.04 D with astigmatism of -1.03 ± 0.72 D. There was a slight hyperopic shift (mean SE 0.14 ± 0.53 D); 94% achieved uncorrected visual acuity ≥20/25 3 months postoperatively. Refractive stability was achieved within 1 month (P < 0.001). Ultrastructurally, the smoothness of the corneal interface was independent of ablation depth (mean irregularity scores A, B, C: 8.8 ± 0.6, 10.3 ± 0.4, 8.7 ± 0.6, respectively; P = 0.88). The increase in IOP during FLEx was similar to that in femtosecond (FS)-LASIK, albeit a twofold duration of raised IOP in FLEx (P < 0.001). CONCLUSIONS: These results suggest that FLEx is predictable and effective in treating myopia and myopic astigmatism. Experimental studies support the early clinical results and safety of this procedure.

Optimization of Fibrin Glue Spray Systems for Ophthalmic Surgery.

PURPOSE: To optimize fibrin glue (FG) spray for ophthalmic surgery using two spray applicators, EasySpray and DuploSpray systems, by varying the distance from point of application and the pressure/flow rate, and to compare the adhesive strength of sutured and sutureless (FG sprayed) conjunctival graft surgery in a rabbit model. METHODS: FG was sprayed on a 0.2 mm-thick sheet of paper using EasySpray by variously combining application distances of 2.5, 5, 7.5, and 10 cm with pressures of 10, 15, and 20 psi. DuploSpray was used at the same distances but with varying flow rates of 1 and 2 L/min. Subsequently, FG was sprayed on porcine corneas and FG thickness was analyzed by histology. In addition, adhesive strength of the conjunctival graft (0.5 × 0.5 cm) attached to the rabbit cornea by sutured and sutureless surgery (FG spray) was compared using a tension meter. RESULTS: Histology measurements revealed that the FG thickness decreased with increases in distance and pressure of spray using the EasySpray applicator on paper and porcine corneal sections. The adhesive strength of the sutured conjunctival graft (41 ± 4.85 [kilopascal] KPa) was found to be higher than the graft attached by spraying (10 ± 2.3 KPa) and the sequential addition of FG (6 ± 0.714 KPa). CONCLUSIONS: The EasySpray applicator formed a uniform spread of FG at a distance-pressure combination of 5 cm and 20 psi. The conjunctival graft attached with sutures had higher adhesive strength compared with grafts glued with a spray applicator. Although the adhesive strength of FG applied through the applicator was similar to the drop-wise sequential technique, the former was more cost effective because more samples could be sprayed compared with the sequential manual technique. TRANSLATIONAL RELEVANCE: The standardization of the spray system for the application of FG in ophthalmology will provide an economical method for delivering consistent healing results after surgery.

Early corneal wound healing and inflammatory responses after refractive lenticule extraction (ReLEx).

PURPOSE: To compare the early corneal wound repair and inflammatory responses after refractive lenticule extraction (ReLEx) and LASIK. METHODS: Eighteen rabbits underwent ReLEx and another 18 underwent LASIK. Each group was divided into three subgroups of six rabbits each and these were subjected to refractive corrections of -3.00 diopters (D), -6.00 D, and -9.00 D. Slit lamp photography, anterior segment optical coherence tomography (AS-OCT), corneal topography, and in vivo confocal microscopy were performed 1 day after surgery. After euthanatization, the corneas were subjected to immunofluorescent staining for fibronectin, CD11b, Ki-67, and TUNEL assay. RESULTS: On slit lamp microscopy, all corneas appeared clear pre- and postoperatively in both ReLEx and LASIK eyes. Corneal topography showed a more significant corneal flattening after LASIK than after ReLEx as the degree of correction was increased (P = 0.916 after -3.00 D correction to P = 0.097 after -9.00 D correction). In vivo confocal microscopy showed less light-scattering particles at the flap interface after ReLEx compared with LASIK. Immunostaining of fibronectin showed a less abundant expression in corneas that underwent ReLEx than LASIK. The differences became more marked as the power of correction was increased. Similar trend was seen in the number of CD11b-positive cells (P = 0.476 after -3.00 D correction to P < 0.001 after -9.00D correction). There was no marked disparity observed in cell death and proliferation between post-ReLEx and -LASIK eyes. CONCLUSIONS: This study has shown that the ReLEx procedure may result in less topographic changes, inflammation, and early extracellular matrix deposition than LASIK, especially at high refractive correction.

Intraocular fluid dynamics and retinal shear stress after vitrectomy and gas tamponade.

PURPOSE: To evaluate fluid dynamics and fluid shear stress on the retinal wall in a model eye after vitrectomy and gas tamponade in relation to saccadic eye movements and sudden head movements and to correlate the results with gas fill fraction (GF). Methods. Analyses was undertaken using high-resolution computational fluid dynamic software. The fluid volume within the eye was discretized using 6 × 10(5) elements and solved with a volume-of-fluid METHOD: The eye was abstracted to a sphere. Vertical and horizontal saccades and sudden rectilinear displacement of the head were examined. GF was varied from 20% to 80% of the eye height filled with gas. RESULTS: Maximum shear stress during horizontal and vertical saccades was 1.0 Pa (Pascal) and 2.5 Pa, respectively, and was dependent on GF. Rapid rectilinear acceleration of the head caused a maximum shear stress of 16 Pa, largely independent of GF. Fluid sloshing within the eye decayed within 0.1 second. Stresses were maximum at the contact line and equator of the eye and were parallel to the direction of motion. CONCLUSIONS: This study predicts that saccadic eye movements and normal head movements after vitrectomy and gas tamponade generate only small fluid shear stresses on the retina that are below published norms for retinal adhesion strength. Sudden, jerking head movements generate fluid shear forces similar to retinal adhesion strength that localize to the area of gas-fluid interface. Fluid sloshing occurs after movement, but rapidly decays on cessation of movement. These results suggest that restrictive posturing after vitrectomy and gas tamponade may be unnecessary. Patients should avoid sudden head movements.

Live or Let Die: Epithelial Flap Vitality and Keratocyte Proliferation Following LASEK and Epi-LASIK in Human Donor and Porcine Eyes.

PURPOSE: To determine the relationship between epithelial flap vitality and stromal keratocyte proliferation following two epithelial refractive techniques: epi-LASIK and laser epithelial keratomileusis (LASEK). METHODS: Human corneas were maintained in organ culture and underwent standard -6.00-diopter ablation. Rates of stromal keratocyte proliferation were detected 1 week postoperative using a Ki67 antibody specific to proliferating cells. Images were captured with a laser scanning confocal microscope and analyzed by a masked observer. Epithelial flap vitality was determined with propidium iodide using fresh porcine corneas. Epithelial flaps were created with Gebauer Epikeratome epi-LASIK or alcohol-assisted LASEK method. Flaps treated with 100% alcohol and uninjured corneas were used as controls. RESULTS: The number of proliferating keratocytes was greatest at 1 week in the epi-LASIK corneas (P<.001). Cell vitality was greatest in the epi-LASIK flaps and declined in the LASEK and 100% alcohol flaps (P<.001). CONCLUSIONS: In this in vitro setting, epi-LASIK results in an epithelial flap with significantly more live cells. There is also a greater number of proliferating stromal cells following epi-LASIK at 1 week. Based on these in vitro observations, epi-LASIK may result in greater levels of haze compared to LASEK.

Use of low-cost video recording device in reflective practice in cataract surgery.

Reflective surgical practice is invaluable for surgeons at all levels of experience. For trainees in particular, every surgical opportunity must be optimized for its learning potential. Recording and reviewing cataract surgery is an invaluable tool. We describe a video recording device that has the advantages of ease of use; low cost; portability; and ease of review, editing, and dissemination, all of which encourage regular use and reflective surgical practice.

Inhibition of transforming growth factor-beta1 and its effects on human corneal fibroblasts by mannose-6-phosphate Potential for preventing haze after refractive surgery.

PURPOSE: To evaluate the action of mannose-6-phosphate (M6P) as an inhibitor of transforming growth factor-beta1 (TGF-beta1) and its effects on human corneal fibroblasts. SETTING: Department of Academic Ophthalmology, Rayne Institute, St. Thomas' Hospital, London, United Kingdom. METHOD: Keratocytes were cultured in serum-containing medium with added TGF-beta1 and in serum-containing medium containing TGF-beta1 with M6P. Controls consisted of cells in serum-containing medium alone and cells cultured in serum-containing medium with M6P. Differentiation of fibroblasts into myofibroblasts was detected by immunohistochemistry for alpha-smooth muscle actin. Images were captured by laser confocal microscopy. RESULTS: The differentiation of cells into myofibroblasts was significantly greater after culture in medium containing TGF-beta1 than in control cultures. Myofibroblast differentiation of cells was significantly reduced when cultured in medium containing TGF-beta1 with M6P (P<.001). CONCLUSIONS: Mannose-6-phosphate significantly reduced TGF-beta1-mediated transformation of human corneal fibroblasts into myofibroblasts; it is a potential modulator of corneal wound healing and may reduce haze after refractive surgery. FINANCIAL DISCLOSURE: Neither author has a financial or proprietary interest in any material or method mentioned.

Anterior chamber instability caused by incisional leakage in coaxial phacoemulsification.

PURPOSE: To establish the percentage of fluid loss through incisions during coaxial phacoemulsification and analyze whether simple measures can reduce it. SETTING: Department of Ophthalmology, Royal Free Hospital, London, United Kingdom. METHODS: This prospective study comprised consecutive patients having routine uneventful cataract surgery. Surgeons used their standard techniques. Incisional leakage was defined by the difference between the total volume of irrigation fluid used and the volume aspirated by the phacoemulsification machine. Nonparametric statistical tests were used to compare phaco-chop techniques performed by consultants, differing only by the duration of the chopper in situ. In 1 technique, the chopper was removed after all the segments were chopped. The other technique required the chopper to be in situ throughout the phacoemulsification stage. RESULTS: The study evaluated 105 patients. The mean incisional leakage was 127 mL +/- 60 (SD) (range 10 to 300 mL), with a significant positive correlation with operation duration and actual phaco time (P<.0001). The mean percentage of incisional leakage was 67% +/- 11% (range 20% to 89%). The mean fluid loss through incisions was 75% in operations performed with the chopper in situ throughout the phacoemulsification stage and 59% when the chopper was removed after all segments were chopped (P<.005). CONCLUSIONS: Significant intraoperative fluid leakage occurred through the incisions. Removal of the chopper after chopping led to a significant reduction in fluid loss and improved chamber stability.

United Kingdom survey of antibiotic prophylaxis practice after publication of the ESCRS Endophthalmitis Study.

The European Society of Cataract & Refractive Surgeons Endophthalmitis Study published preliminary results in 2006 showing a near 5-fold decrease in the rates of postoperative endophthalmitis with the use of intracameral cefuroxime. The study findings have generated considerable controversy, and 1 year later its recommendations had been heeded by only 6% of American Society of Cataract and Refractive Surgery (ASCRS) members. This poll sought to gauge the uptake among surgeons in the United Kingdom and survey their response to its findings. Fifty-five percent of respondents were using intracameral cefuroxime; 48% had switched after publication of the ESCRS study. Of those remaining, 68% reported their main concern was the risk for dilution errors in the absence of a commercially preformulated preparation, with 67% stating they would switch if such a product became available. Sixty-eight percent considered the lack of a subconjunctival cefuroxime treatment arm within the study a major methodology flaw. Sixty-seven percent said they do not consider penicillin allergy a contraindication to intracameral cefuroxime use, with the remaining 33% opting for alternative antibiotic prophylaxis. The majority of United Kingdom and Ireland Society of Cataract and Refractive Surgeons members have switched to intracameral cefuroxime, despite the absence of previously preferred practice in the study design. The major barrier to its further use appears to be the lack of a commercially available preformulated preparation.

Blow-back technique for confirmation of peripheral iridectomy patency.

We describe a simple blow-back technique that can be used to confirm the patency of a peripheral iridectomy. Flow reversal is used to flush the iridectomy specimen onto the corneal surface to look for the presence of iris pigment epithelium in small basal iridectomies fashioned using a vitrector.