Rituals to prevent development of visually significant corneal haze after photorefractive keratectomy (PRK) or cross-linking (KXL)

Session Details

Session Title: Keratoconus & Secondary Ectasia

Session Date/Time: Sunday 15/09/2019 | 08:00-10:00

Paper Time: 09:27

Venue: Free Paper Forum: Podium 2

First Author: : P.Ahuja INDIA

Co Author(s): :    R. Shetty   A. Ghosh   S. Sethu   P. Khamar                    

Abstract Details

Purpose:

PRK is a safe, predictable refractive procedure with excellent outcomes. Similarly, KXL has been effective in the management of keratoconus. However, the development of unwanted corneal haze in both these procedures results in suboptimal clinical outcomes. Hence, confounding our otherwise effective management strategies. Multiple factors such as ocular surface inflammatory status, nutritional deficiencies, systemic allergy and molecular predisposition could attribute to the development of corneal haze post-PRK or KXL. Thus, we evaluated the various potential risk factors status in patients who developed post-operative haze and also investigated whether appropriate management of these risk factors mitigated the development of post-operative haze.

Setting:

The study includes both retrospective arm and a prospective observational case series arm, and was conducted at a tertiary eye care institute with prior ethics committee approval.

Methods:

Arm-1: Association between post-operative corneal haze and risk factors (preoperative OSDI scores>30; contact lens intolerance; meibomian gland dysfunction; serum IgE>300IU/ml; serum vitamin- D; molecular profile in epithelium–in a few) was retrospectively analysed in 250 PRK and 180 KXL patients. Haze was assessed by slit-lamp photographs and densitometry maps. Arm-2: Incidence of haze was assessed after management of risk factors pre-operatively (by either topical steroids and thermal/light pulsation therapy of ocular surface inflammation or discomfort; vitamin-D supplementation; desensitization immunotherapy for allergy) and post-operatively (oral doxycycline; topical steroids / cyclosporine) in 160 and 120 patients undergoing PRK and KXL respectively.

Results:

Arm-1: It was observed that the 8% of PRK and 12% of KXL patients developed significant post-operative haze at 6 months. These patients pre-operatively exhibited unfavourable risk factor status. Further, intraoperative corneal epithelium in these patients exhibited altered expression of a distinct set of genes (PREX1, PXDN, SOX17, WNT3, aSMA) that predispose to haze. Arm-2: Pre-operative management of the risk factors exhibited a drop in the incidence of corneal haze to 0.6% PRK and 1% KXL of patients. We also observed with a altered tear fluid inflammatory and pro-nociceptive cytokines such as IL-1β, IL-6, IL-17A, TNFα, IFNγ and higher IL-10.

Conclusions:

Post-operative corneal haze has eclipsed the clinical success of PRK and KXL. In the current study we have identified a set of pre-operative risk factors that would contribute to the development of haze. Increased inflammatory factors are well known to drive fibrosis. Vitamin D dampens inflammation and improves corneal wound healing response. We have also observed a unique set of genes that when altered predispose to haze. Based on our findings, following a stepwise ritualistic approach to manage ocular surface inflammation, allergy & nutritional deficiencies prevent post-operative corneal haze. Thus, improving patient satisfaction and success of PRK and KXL.

Financial Disclosure:

None