Intraocular Light Scatter in Eyes with the Boston Type 1 Keratoprosthesis

Purpose: The Boston keratoprosthesis (KPro) is the most commonly used artificial cornea. It has been proven to be successful for severe corneal disease not amenable to keratoplasty. We have observed our patients reporting debilitating glare despite attaining good visual acuities. This motivated us to objectively measure light scatter in eyes with a KPro. Methods: Light scatter was measured in 21 eyes with the Boston type 1 KPro with a VA of 20/150 or better and was compared with 13 healthy control eyes using the Oculus C-Quant device (Arlington, WA). Eyes were also measured using an occluder contact lens. Results: Light scatter (quantified as the logS value) was significantly higher in the KPro group than in the control (2.34 ± 0.15 vs. 1.29 ± 0.17, P , 0.001). The polymethylmethacrylate (PMMA) KPro group (16 eyes, logS 2.49 ± 0.19) but not the titanium group (5 eyes, logS 1.87 ± 0.15) had significantly higher light scattering than the control. The use of an occluder contact lens significantly decreased light scatter in eyes with a PMMA backplate (n = 11, logS 1.71 vs. 2.42, P = 0.028). Conclusion: This study confirms that intraocular light scatter is increased in KPro eyes. Possibly because of its opaque nature, the titanium backplate model seems to produce less light scatter than does the PMMA model. Occluder contact lenses reduced light scatter significantly in the PMMA KPro and could be a treatment option for symptomatic patients.Fil: Karas, Faris I.. University of Illinois; Estados UnidosFil: Arteaga, Andrea. University of Illinois; Estados UnidosFil: Barrionuevo, Pablo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Investigación en Luz, Ambiente y Visión. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Investigación en Luz, Ambiente y Visión; ArgentinaFil: Cao, Dingcai. University of Illinois; Estados UnidosFil: McAnany, J. Jason. University of Illinois; Estados UnidosFil: Shorter, Ellen. University of Illinois; Estados UnidosFil: Cortina, Maria S.. University of Illinois; Estados Unido

Intraocular Light Scatter in Eyes with Boston Type 1 Keratoprosthesis

Purpose: Boston Keratoprosthesis (KPro) is the most commonly used artificial cornea. It has been proven to be successful for severe corneal disease not amenable to keratoplasty. We have observed our patients complain of debilitating glare despite attaining good visual acuities. This motivated us to objectively measure light scatter in eyes with KPro. Methods: Light scatter was measured in 21 eyes with Boston KPro Type 1 with VA of 20/150 or better and was compared to 13 healthy control eyes using OCULUS C-Quant device (Arlington, WA). Eyes were also measured with the use of an occluder contact lens. Results: Light scatter (quantified as logS value) was significantly higher in the KPro group compared to the control (2.34 ± 0.15 vs. 1.29 ± 0.17, p < 0.001). PMMA KPro (16 eyes, logS 2.49 ± 0.19) but not the titanium group (5 eyes, logS 1.87 ± 0.15) had significantly higher light scattering than the control. The use of an occluder contact lens significantly decreased light scatter in eyes with PMMA-backplate (n=11, logS 1.71 vs 2.42, p =0.028). Conclusion: This study confirms that intraocular light scatter is increased in KPro eyes. Possibly due to its opaque nature, the titanium backplate model appears to produce less light scatter than PMMA model. Occluder contact lenses reduced the light scatter significantly in PMMA KPro and could be a treatment option for symptomatic patients

Complications.

<p>Complications.</p

Five year outcomes of Boston type I keratoprosthesis as primary versus secondary penetrating corneal procedure in a matched case control study

<div><p>Despite improved retention and reduced complication rates paving the way for the current expansion of applications and surge in prevalence for the Boston type I Keratoprosthesis (KPro), the most frequent indication for its implantation today remains prior graft failure. The purpose of this study is to evaluate the long-term outcomes of primary KPro and compare to secondary implantation in a matched cohort study. This study included patients who underwent KPro implantation in a single center by two surgeons between July 2008 and October 2014. All eyes with KPro implantation as the primary procedure with a minimum follow up of 12 months were matched with eyes with same preoperative diagnoses that underwent secondary KPro implantation. Main outcomes included visual acuity and device retention. A total of 56 eyes were included with 28 eyes in each group. Mean follow up was 5.0 years for both groups. Twenty-nine percent (8) of the eyes in the primary group had a diagnosis of chemical or thermal injuries, 25% (7) aniridia, 18% (5) autoimmune disease, 4% (1) infectious keratitis/neurotrophic cornea, 7% (2) gelatinous corneal dystrophy, 7% (2) ectrodactyly ectodermal dysplasia/limbal stem cell deficiency, and 11% (3) uveitis/hypotony. Sixty-one percent (17) of the eyes in the primary group and 39% (11) in the secondary group maintained a final best-corrected visual acuity of 20/200 or better at a mean follow up of 5.0 years; the probability of maintaining best-corrected vision is 0.83 and 0.49 for primary and secondary groups at 5.0 years (p = 0.02). There is no statistically significant difference between groups in device retention (p = 0.22) or postoperative complication rates (p >0.05). This study demonstrates that Boston KPro implantation may be successful as a primary procedure in patients at high risk of failure with traditional penetrating keratoplasty. The device has a good long-term retention rate and visual outcomes are promising however a larger study is needed for more definitive results.</p></div

Survival of visual acuity.

<p>Graph showing best-corrected visual acuity survival curves for both primary and secondary groups. X-axis demonstrates post-operative months, and y-axis demonstrates survival of best-corrected visual acuity (e.g 1.0 = 100% of the eyes maintaining best-corrected post-operative visual acuity). P-value was calculated using Log-rank test. Table below shows the number of eyes followed at each time point.</p

Device retention.

<p>Graph showing KPro survival curves for both primary and secondary groups. X-axis demonstrates post-operative months, and y-axis demonstrates KPro survival (e.g. 1.0 = 100% of the eyes with device retention). P-value was calculated using Log-rank test. Table below shows the number of eyes followed at each time point.</p

Snellen visual acuity outcomes.

<p>Snellen visual acuity outcomes.</p

LogMAR visual acuity outcomes.

<p>LogMAR visual acuity outcomes.</p

Baseline characteristics of eyes of patients who underwent Boston type I keratoprosthesis as a primary and secondary procedure.

<p>Baseline characteristics of eyes of patients who underwent Boston type I keratoprosthesis as a primary and secondary procedure.</p