Surgical Management of Severe Retinopathy of Prematurity

In the experience of many seasoned ophthalmologists who have followed eyes afflicted with advanced retinopathy of prematurity (ROP), vitreous organization is believed to be a harbinger of bad news in the form of a tractional retinal detachment. Although the exact rate of progression from vitreous organization to retinal detachment is unknown, this factor suggests that vitrectomy surgery for vitreous organization in ROP may be beneficial for certain patients. This position is controversial, but several case series have reported that vitrectomy surgery for Stage 4A (macula-sparing) retinal detachments can be very successful with both excellent anatomic and visual results (Ophthalmology. 2004;111:2271-2273, Ophthalmology. 2005;112:1569-1573). Moreover, management of retinal detachments in infants with ROP has improved significantly and now primarily involves vitrectomy surgery. This article will explore the uses of vitrectomy surgery to treat ROP prior to retinal detachment using information gleaned from observing the organization of vitreous collagen structures.

Clues from Vitreous Collagen

Traditionally, advanced ROP is treated with ablation of the peripheral avascular retina, most commonly using laser through an indirect ophthalmoscope delivery mechanism. Despite treatment of high risk pre-threshold ROP, as many as 9.1% of eyes will progress to an unfavorable structural outcome despite appropriate laser treatment (Arch Ophthalmol. 2003;121:1684-1694). Additionally, many ROP-afflicted eyes progress beyond Stage 4A, where the visual prognosis is much less favorable, and as many as 10% to 20% of eyes undergoing vitrectomies for Stage 4A detachments have poor outcomes due to progressive retinal detachment.

Fortunately, an understanding of important clinical findings that portend a high probability of retinal detachment in eyes that have undergone ablative therapy for ROP is developing. Clues as to which eyes are likely to proceed to a retinal detachment are frequently seen in visible organization of the vitreous collagen (Am J Ophthalmol.2005;140:214-222).

Organization of vitreous collagen, which is seen clinically as white, fibrous-like vitreous structures, can appear in basically 2 areas. The first, most common, and easiest to identify structure occurs in the area of the ridge tissue above the vascular/avascular junction. Visible organization of the vitreous collagen develops above the vascular-avascular junction and proceeds in a circumferential fashion. As it progresses, it can lead to elevation of the retina along the ridge and later to a progressive retinal detachment. Organization of the vitreous collagen can also involve tissue that emanates from the optic disc, resembling a stalk.

The Role of Traction

A development that is sometimes obvious during indirect ophthalmoscopic examination of the fundus, but which is most easily appreciated during vitrectomy surgery, is the appearance of tentacles that may spread out from this stalk to the periphery.  Contraction of these tentacles produces traction on the peripheral retina, ultimately contributing to the development of a tractional retinal detachment. In addition to producing a retinal detachment, a tractional retinal detachment in ROP often results in a dragging of the retinal vessels which may produce foveal ectopia.

Foveal ectopia and dragging seem to be the result of the organization and contraction of the vitreous collagen, specifically the posterior hyaloid, which is difficult, if not impossible, to remove by vitrectomy techniques without the aid of enzymatic manipulation of the vitreous.  Foveal ectopia and dragging often develop even in eyes that have not developed a retinal detachment. No effective surgical intervention is available to remedy these tractional forces, which can have a substantially deleterious effect on vision.

The Case for Vitrectomy

At present, vitrectomy surgery is not recommended until a retinal detachment develops.  Documented improvements in anatomic and visual results from earlier intervention of small retinal detachments and an increase in complications during vitreous surgery for more advanced ROP-related retinal detachments have prompted some researchers to postulate that employing vitrectomy to manage advanced vitreous organization prior to the development of obvious retinal traction and detachment might substantially benefit selected eyes (Retina. 2003;23:322-329) by reducing or eliminating foveal ectopia and by preventing detachment of the fovea, which is detrimental to visual acuity.  It is also well accepted that the eyes undergoing vitreous surgery for stage 4A ROP retinal detachment do much better than eyes undergoing vitreous surgery for stage 4B stage 5 retinopathy of prematurity.

Despite this, some eyes still develop advanced retinal detachments that are poorly responsive to vitreous surgery. The overall prognosis of such eyes could potentially be improved, if vitreous surgery were performed in the presence of advanced vitreous organization and prior to a retinal detachment or obvious dragging/foveal ectopia. The risks of vitrectomy, although not insignificant, are relatively low. 

Complications of Vitreous Surgery

Endophthalmitis, retinal tears, and lens complications are the most severe and/or common complications of vitreous surgery in a young eye, and the risk of each of these complications is very low.  Despite this, until further information is available, vitreous surgery for ROP should be reserved for eyes that have developed a retinal detachment; eyes that develop vitreous organization after laser ablation therapy for ROP should also be monitored very closely for signs of a retinal detachment. Further investigation of the benefits or drawbacks of vitreous surgery for the treatment of advanced vitreous organization may be warranted in order to mitigate its potentially detrimental implications on the developing retina.

References

Author Disclosure

The author states that he has no financial relationship with the manufacturer or provider of any product or service discussed in this article or with the manufacturer or provider of any competing product or service.