Commentary: Cataract in retinopathy of prematurity - Prevention is the best cure

Cataract in babies at a very young age, especially in association with retinopathy of prematurity (ROP), is not as innocuous as it is in the elderly and needs prompt and effective treatment to establish a clear visual axis, prevent deprivational amblyopia, and allow normal visual maturation. Visual rehabilitation after cataract surgery in babies presents many problems that require long-term management and commitment both by the parents as well as the treating ophthalmologist. The current article (Manuscript number: IJO_125_21)[1] throws light on the underlying etiologies as well as management of cataracts associated with ROP.

One of the most common complications of cataract surgery in childhood is open-angle glaucoma (OAG) with a reported incidence of 6%–50%.[2] In addition, younger age at the time of cataract removal is the most important risk factor for glaucoma.[3] The various hypothesis postulated for development of glaucoma after cataract extraction include posterior synechiae on the anterior hyaloid face, resulting in aqueous blockage, and Vitreous in angles causing dysgenesis of anterior chamber angle, resulting in subsequent glaucoma.[4] It may not always present in the early postoperative period and may silently creep up even years after cataract extraction resulting in optic disc pallor and cupping if not diagnosed and treated early.[5] OAG has been reported even after pars plana vitrectomy (PPV) for ROP even when the lens has been preserved. Increased risk of glaucoma after PPV has been attributed to increased oxygen diffusion to the angle, resulting in degeneration of the trabecular meshwork.[6] Nudleman et al.[7] reported the incidence of glaucoma to be 10% in eyes undergoing lens-sparing vitrectomy (LSV). This incidence of glaucoma increases with increased severity of the disease, with 6.9% in stage 4A, 12.0% in stage 4B, and 33.3% in stage 5 ROP eyes undergoing LSV. In ROP, lens removal may be necessary as a part of the surgical procedure in stage 4 and 5; the risk to develop glaucoma increases by 2.76 times in eyes undergoing lensectomy during ROP surgery.[7]

Significant myopic shift at an average of −3.07 D (±2.51) in pseudophakes and −8.75 D (±1.84) in aphakes after cataract surgery was reported by Ezisi et al.[8] and is more often seen in younger children undergoing cataract extraction. Myopic shift may also be an early sign of glaucoma in babies and should be carefully investigated and followed up. Uncorrected refractive error combined with various degrees of cerebral visual impairment due to hypoxic ischemic encephalopathy in some of these babies with ROP can become challenging to manage.

Prevention of lens trauma as well as meticulous attention to save the clear lens during the various treatment interventions of ROP cannot be overemphasized.

Some cardinal points to safeguard the lens while managing ROP are discussed below:

1. Diode laser for peripheral retinal photocoagulation, especially in presence of Tunica vasculosa lentis, may reduce the incidence of cataract formation in ROP babies following laser.[9]

2. Extensive heavy confluent burns especially in aggressive ROP (AROP) can be completed in multiple sittings if necessary to prevent anterior segment ischemia, which may rarely occur following laser procedure in ROP.

3. During intravitreal anti-VEGF injections, the injection should be administered at 0.75-1 mm posterior to limbus, directing the needle toward the mid vitreous cavity.

4. Babies are straddled and gently grasped at the head to prevent inadvertent jerky movement of the head during the injection. Keeping the hand steady during entry with one finger at the plunger for injection helps to avoid movement once inside the eye.

5. Paracentesis after injection of intravitreal anti-VEGF is best avoided. The volume of anti-VEGF injected is very minimal in babies and paracentesis is not necessary and can be hazardous.

6. During LSV, the “stop and slide” technique of making sclerotomies can be applied to prevent inadvertent touch to the lens with the trocar in ROP eyes that have small axial length.[10]

7. External fixation of the infusion cannula prevents inadvertent movement of the cannula due to torque. In some cases, direct entry for the upper sclerotomies instead of using the trocar cannula system can allow navigation in very small eyes in 1 – 2-month-old babies without the risk of hitting the lens.

8. Selection of the sclerotomy sites with a dilated examination under anesthesia prior to surgery is recommended so that the need to go across the lens to reach fibrovascular proliferation is minimal.

9. Adding an encirclage as and when necessary during surgery to support the peripheral traction.

10. Use of indirect laser photocoagulation for laser to the peripheral retina during surgery instead of endolaser is safer.

11. Removing the lens for a minimal peripheral lens touch may not always be necessary if it does not compromise the intraoperative or postoperative view of the retina; pediatric lenses are more resilient to cataract formation as compared to adult lenses.

Management of ROP and associated cataract and/or aphakia is a team effort and needs the cooperation of parents for a lifetime. Educating parents can be vital to include them as partners in this venture.