Conventional Versus Accelerated Collagen Cross-Linking for Keratoconus: A Comparison of Visual, Refractive, Topographic and Biomechanical Outcomes.

OBJECTIVE: The aim was to compare the visual, refractive, topographic and biomechanical outcomes in patients with progressive keratoconus treated with either conventional or accelerated crosslinking at one year follow up. METHODS: It is a prospective, non-randomised interventional study of 76 patients who underwent conventional (CXL; 3mW/cm2 for 30 minutes) or accelerated cross linking (KXL; 30mW/cm2 for 4 minutes) for progressive keratoconus. Baseline and postoperative visual acuity, manifest refraction, corneal topography, pachymetry, endothelial cell density and biomechanical parameters of corneal hysteresis and corneal resistance factor were evaluated and compared. RESULTS: The 2 groups were comparable in terms of uncorrected and best corrected visual acuity and spherical equivalent. Both groups showed no significant increase in K1, K2 and Kmean from baseline at 12 months. There was also no difference between the CXL and KXL group for postoperative corneal topography as well as central and minimal pachymetry up to 12 months. There was a significant increase in both corneal hysteresis (0.62mm Hg, P=0.04) and corneal resistance factor (0.91mm Hg, P=0.003) in the KXL group at 12 months but not in the CXL group. There was no significant endothelial cell loss throughout follow up in both the groups. CONCLUSION: We have established comparability of the 2 protocols in stabilizing the progression of keratoconus. Our findings also suggested an added biomechanical advantage of accelerated crosslinking at 1 year follow up.

Endothelial approach ultrathin corneal grafts prepared by femtosecond laser for descemet stripping endothelial keratoplasty.

PURPOSE: To investigate the quality of the ultrathin corneal grafts prepared by femtosecond laser from the endothelial side for Descemet stripping endothelial keratoplasty. METHODS: Thirty human corneoscleral buttons were cut from the endothelial side by laser Doppler velocimetry (LDV) with or without viscoelastic materials coating. Two cutting depths were selected: 70 and 90 µm. The postcut endothelial count was determined by specular microscopy, and the graft thickness was evaluated by anterior segment optical coherence tomography. The endothelial viability was determined using Trypan blue/Alizarin red staining, calcein-AM/EthD-1 live/dead cell assay, and scanning electron microscope (SEM). The graft interface smoothness was evaluated by SEM. Another 18 corneoscleral buttons were used as controls for the comparisons. RESULTS: The overall targeted cutting depth and achieved cutting depth were significantly highly correlated (r = 0.84). The central to peripheral corneal thickness ratio was 0.976 and 0.998 for the 70- and 90-µm grafts. The percentage of the damaged endothelial cells assessed by vital staining and SEM showed the 70-µm grafts had noticeably more endothelial damage compared with the 90-µm grafts. But the damage was significantly reduced, to the control corneas level, after coating the endothelium with Viscoat. The 90-µm grafts had a slightly rougher graft interface than the 70-µm grafts, but all the grafts dissected by a Chansue dissector exhibited a generally smooth interface. CONCLUSIONS: The corneal endothelial grafts prepared by LDV femtosecond laser with endothelial approach produced consistently ultrathin grafts in uniform shape with high accuracy and good endothelial and stromal interface quality.

Risk factors for donor endothelial loss in eye bank-prepared posterior lamellar corneal tissue for descemet stripping automated endothelial keratoplasty.

PURPOSE: The aim of this study was to investigate donor, tissue, and precut procedure risk factors for endothelial cell density (ECD) loss in posterior lamellar corneal tissue preparation by an eye bank for Descemet stripping automated endothelial keratoplasty. METHODS: A total of 259 corneoscleral rims precut by the Singapore Eye Bank from October 2011 to August 2013 were evaluated. Donor characteristics, tissue characteristics, and precut procedure parameters were analyzed. RESULTS: The mean donor age was 57.18 ± 11.35 years, and the mean cutting transition time was 4.16 ± 0.75 seconds. The mean ECD was 2826 ± 225 and 2787 ± 224 cells per square millimeter before and after precutting, respectively, with an average ECD change of -1.38% ± 3.28%. The precutting procedure failure rate was 1.2%. Mutivariate regression analysis showed that an older donor age, a higher ECD before cutting, and a slower cutting transition speed were significant factors. Corneas with an ECD >2800 cells per square millimeter before precutting, cutting transition time >5.5 seconds, and corneas with donor age >65 years were significantly more likely to have greater than 5% ECD loss after precutting (odds ratio, 6.42, 1.66, and 1.62; 95% confidence interval, 1.44-29.43, 1.45-2.72, and 1.66-5.82, respectively). Donor source, death-to-preservation time (range, 0.67-10.88 hours), death-to-precutting time (range, 0-7 days), and graft thickness (range, 43-232 µm) were not statistically significant factors. CONCLUSIONS: The ECD loss in the precut tissue prepared by the eye bank was very low. The risk factors identified provide better understanding of how to improve the quality and safety profiles when preparing graft tissue for Descemet stripping automated endothelial keratoplasty.

Descemet stripping automated endothelial keratoplasty in complex eyes: results with a donor insertion device.

PURPOSE: Descemet stripping automated endothelial keratoplasty (DSAEK) in eyes with complex anterior segment pathology or previous intraocular surgery is at risk of surgical complications and graft failure. We evaluated the use of the EndoGlide donor insertion device for DSAEK in these complex cases. METHODS: This was a retrospective interventional series of 45 consecutive eyes with endothelial dysfunction and higher risk ocular comorbidities that underwent DSAEK with the EndoGlide. We included eyes with aphakia, glaucoma surgery, prior vitrectomy, anterior chamber intraocular lenses, failed cornea grafts, and primary angle closure glaucoma. Demographic and clinical details, intraoperative and postoperative complications, and postoperative graft clarity, and endothelial cell density (ECD) loss were documented. RESULTS: The average age was 62 years (range, 16-88 years), and the majority were Chinese (n = 28). The commonest risk factors identified were previous trabeculectomy (n = 13) and failed penetrating keratoplasty (n = 12). Preoperative donor ECD averaged 2790 ± 230 cells per square millimeter and modal graft diameter was 9.0 mm (range, 7.75-9.75 mm). One eye (2.2%) had primary graft failure, and 3 eyes (6.7%) had graft dislocation. Another 3 eyes suffered late graft failure within the first year and 2 were in eyes with an anterior chamber intraocular lenses. At 6 months, the mean ECD was 2363 + 242 cells/mm2 and the mean ECD loss was 17.9% (n = 16). By 12 months, the mean ECD was 2098 + 462 cells/mm2 and the mean ECD loss was 27.0% (n = 20). CONCLUSIONS: Donor insertion with this device can help address inherent intraoperative challenges and minimize endothelial cell damage during DSAEK in complex cases.

Comparison of outcomes of conventional WaveLight(®) Allegretto Wave(®) and Technolas(®) excimer lasers in myopic laser in situ keratomileusis.

OBJECTIVE: To compare the results of laser in situ keratomileusis for myopia using WaveLight(®) Allegretto Wave(®) Eye-Q(®) and Technolas(®) 217z excimer lasers. METHOD: A retrospective, comparative case series of 442 eyes matched for age and myopia: half each were treated with Allegretto's wavefront-optimized algorithm and Technolas PlanoScan. Outcome measures were postoperative mean logarithm of the minimum angle of resolution (logMAR) uncorrected visual acuity (UCVA), manifest refraction spherical equivalent (MRSE), cylinder, safety and efficacy indices, refractive predictability, and optical zone size selection. Refractive predictability of a subgroup treated for -2.50 to -4.0 diopter (D) was analyzed separately. RESULTS: At mean follow-up of 80.5 days, mean logMAR UCVA, mean MRSE and mean postoperative cylinder were 0.02 ± 0.07 (range -0.12 to 0.30), 0.27 ± 0.36 D (range -1.25 to 1.50 D) and -0.33 ± 0.30 D (range 0.00 to -1.50 D) for Allegretto versus 0.02 ± 0.08 (range -0.12 to 0.40), 0.095 ± 0.47 D (range -1.25 to 1.13 D) and -0.44 ± 0.5 2 D (range 0.00 to -2.25 D) for Technolas (P = 0.98, 0.80 and 0.006). Mean safety and efficacy indices were 1.05 ± 0.13 (0.75-1.33) and 0.97 ± 0.13 (0.50-1.33) for Allegretto and 1.07 ± 0.14 (0.75-1.49) and 0.97 ± 0.17 (0.40-1.49) for Technolas (P = 0.23 and 0.69). Proportions of eyes achieving postoperative MRSE within ±1.0 D, ±0.5 D, and ±0.25 D were 98.2%, 91.9% and 75.6% for Allegretto and 99.1%, 97.8% and 72.4% for Technolas (P = 0.68, 0.20 and 0.51). Mean optical zone size selected was 6.48 ± 0.10 mm (range 6.0-6.5 mm) for Allegretto and 6.38 ± 0.19 mm (range 5.6-6.6 mm) for Technolas (P < 0.001). Of the subgroup with treatment between -2.5 and -4.0 D, 86.8% and 58.5% of eyes treated with Allegretto achieved postoperative MRSE within ±0.50 D and ±0.25 D versus 70.4% and 44.4% for Technolas (P = 0.006 and 0.057). CONCLUSION: No differences were seen in postoperative mean logMAR UCVA, MRSE, safety and efficacy indices between the two lasers. Allegretto produced less residual astigmatism, possibly improved refractive predictability, and required smaller optical zone selection.

Contact lens characteristics and contrast sensitivity of patients with keratoconus.

OBJECTIVES: The aim was to describe the contact lens characteristics and contrast sensitivity of patients with keratoconus managed conservatively with contacts lenses at a tertiary eye center in Singapore. METHODS: A prospective cross-sectional study of 116 patients with clinically evident or suspected keratoconus (on videokeratography) recruited over 11 months. Demographic and medical details, visual acuity (VA) and refraction, corneal topography and contact lens characteristics were documented. Contrast sensitivity with contact lenses was performed with the Vision Contrast Test System 6500 under standardized conditions. RESULTS: Overall, 67% of the study patients were wearing contact lenses. Of the 129 eligible eyes analyzed, there were 108 eyes with keratoconus and 21 eyes with keratoconus suspect, and 94% were fitted with rigid gas permeable (RGP) lenses. Proprietary keratoconus design lenses were fitted in 74.9% of keratoconus eyes and 30.0% of suspect eyes. With contact lens wear, 83.3% of keratoconus eyes and 100% of suspect eyes achieved 0.3 vision. Mean contrast sensitivity curves of eyes with keratoconus and keratoconus suspect were found to be within normal, although contrast sensitivity in the keratoconus group was consistently lower. CONCLUSIONS: Most of our patients were managed conservatively with contact lenses, and keratoconus design RGP lenses were the most common type fitted. Good VA can be achieved, but patients with keratoconus may still experience a reduction in contrast sensitivity.

Keratoconus in Asians: demographics, clinical characteristics and visual function in a hospital-based population.

BACKGROUND: To describe the demographics, clinical characteristics and visual function of Asian patients with keratoconus managed in a tertiary eye centre. DESIGN: Prospective cross-sectional study. PARTICIPANTS: 116 patients with clinically evident or suspected keratoconus (on videokeratography) recruited over 11 months. METHODS: A standardised interview, full ophthalmic examination, refraction and corneal topography were performed. Visual function was assessed with the VF-14 questionnaire. MAIN OUTCOME MEASURES: Demographics, clinical characteristics and visual function. RESULTS: Mean age of our patients was 29.5 ± 9.40 years on enrolment, 62.9% were male, and the ethnic distribution was 60.3% Chinese, 13.8% Malays and 9.5% Indians. Clinically evident keratoconus was present bilaterally in 65 patients (56.0%) and unilateral keratoconus in five patients (4.3%). Five patients (4.3%) had a family history of keratoconus. The majority of patients were managed with contact lenses (60.8%) or glasses (24.5%). Eye rubbing was common (68%) as were asthma (26.3%) and eczema (18.4%). Conical protrusion was the commonest sign (75.3%). The mean cylinder was higher in keratoconus eyes compared with keratoconus suspect eyes (-4.01 vs. -1.27, P < 0.001), and best-corrected visual acuity was poorer (0.19 vs. 0.05, P < 0.001). Unaided visual acuity was significantly worse with increasing age (P = 0.016). On the VF-14, 32% scored 90 or less (out of 100), reflecting difficulties with vision-related daily activities. CONCLUSIONS: Our Asian patients with keratoconus had similar demographic and clinical characteristics to patients in Western populations. Even with apparently good visual acuity, some patients still experience substantial impairment in vision-related activities.

Deep lamellar keratoplasty for acanthamoeba keratitis.

PURPOSE: To describe deep lamellar keratoplasty (DALK) as a surgical alternative to penetrating keratoplasty in the management of unresponsive Acanthamoeba keratitis. METHODS: Interventional case report. We performed DALK in a patient with Acanthamoeba keratitis unresponsive to intensive antimicrobial therapy. A modified form of the Anwar big-bubble technique, with total corneal stromal removal down to Descemet membrane, was successfully performed without entry into the anterior chamber. Subsequent delay in graft epithelialization relating to ocular surface toxicity from prolonged antiacanthamoebal topical therapy required a secondary amniotic membrane patch graft. RESULTS: No recurrence of Acanthamoeba infection occurred after surgery. Reepithelialization after the amniotic membrane patch graft was successful, and full visual recovery occurred, resulting in a best-corrected visual acuity of 20/20. CONCLUSIONS: DALK with total removal of infected stromal tissue may be performed in medically unresponsive cases of Acanthamoeba keratitis, which ordinarily may require penetrating keratoplasty. Advantages of DALK in infectious keratitis include less risk of intraocular entry of infectious organisms at the time of surgery and the potential for improved graft survival rates caused by less endothelial rejection and failure.