Optical Coherence Tomography Findings in Patients with Degenerative Retinoschisis and Symptomatic Retinal Detachment

Introduction

Degenerative retinoschisis is an acquired peripheral retinal disease occurring more often in hyperopic eyes.¹ Retinoschisis may be grouped into hereditary and secondary forms based on the underlying diseases.¹ Central, peripheral, and combined retinoschisis are distinguished according to their localization.² The subset of combined retinoschisis-retinal detachment occurs in approximately 6.4% of eyes in patients presenting with degenerative retinoschisis in a series published by Byer.² In clinical practice, it is sometimes difficult to assess the presence or extent of associated retinal detachment in patients presenting with degenerative retinoschisis. A better understanding of retinoschisis in these cases may be possible using optical coherence tomography (OCT), which is based on the principle of low-coherence interferometry.³ Currently there are few studies describing the combination of degenerative retinoschisis and retinal detachment using OCT.⁴ The purpose of the current study is to describe the OCT features of 4 patients with this condition.

Design and Methods

Stratus optical coherence tomography III was utilized to examine these patients using scans with a 5 mm line along both vertical and horizontal axis through the macula and the peripheral schisis areas.

Results

Four patients (2 men and 2 women) with degenerative retinoschisis and symptomatic retinal detachment were identified and underwent testing with OCT at the Bascom Palmer Eye Institute. The patients were a mean of 52-years-old (range 37 to 62). The period from the onset of symptoms of retinal detachment ranged from 1 week to 1 year after retinoschisis was first diagnosed. Best corrected visual acuity ranged from 20/25 to 20/200 at the initial visit. The clinical features, ocular symptoms, and outcomes are listed in the table.

Table: Clinical Data of Patients with Degenerative Retinoschisis and Symptomatic Retinal Detachment

Case Reports

Case 1

A 57-year-old man was referred for a second opinion due to further loss of vision in the right eye from 20/80 to 20/200 and an increase in macular thickness from 224 to 601 microns observed in the OCT. Central visual loss was attributed to a macular epiretinal membrane. The peripheral retina showed degenerative retinoschisis in the superior temporal quadrant and a concurrent rhegmatogenous retinal detachment with a large outer layer retinal break (Fig. 1A). OCT confirms the presence of subretinal fluid in the superior temporal quadrant where there has been a large outer layer break causing the residual outer retina to “roll under” the remaining inner retina layer (Fig. 1A). The right eye underwent pars plana vitrectomy, membrane peeling of the macular epiretinal membrane, internal drainage of subretinal-schisis fluid, fluid air exchange, laser treatment to the area of retinoschisis and retinal detachment, and 16% C₃F₈ gas injection. Visual acuity 3 months after surgery increased to 20/30 in the right eye (RE). Posterior segment examination of the RE showed mild pigmentary alterations in the macula and no epiretinal membrane. The peripheral retina remains attached and a chorioretinal scar in the superior temporal quadrant corresponding to the previous area of retinoschisis was observed (Fig. 1B).

Figure 1. (A) Initial Examination of Case 1. A 57-Year-Old Man, Best-Corrected Visual Acuity is 20/200 in the Right Eye. Left: Montage Photograph of the Right Eye Showing Retinal Detachment and Retinoschisis in the Superior Temporal Quadrant. Right: OCT Image Showing Retinoschisis in the Superior Temporal Quadrant and a “rolled Under” Outer Retina Layer. There is a Substantial Amount of Subretinal Fluid Under the Remaining Overlying Thin Inner Retina Layer. (B) Left: Post-Operative Montage Photograph of Case 1 Showing Retinal Reattachment with RPE Atrophy and a Demarcation Line. Right: OCT Cross Section of the Combined Retinoschisis Retinal Detachment Area After Surgery was Performed Confirming Retina is Attached. The Remaining Inner Retina is Thin and OCT Confirms the Absence of Subretinal Fluid After Surgery.

Case 2

A 62-year-old woman was referred with recent visual loss from recurrent retinal detachment with macular involvement in the left eye (Fig. 2A). On examination visual acuity was 20/300 in the left eye. The posterior segment examination showed combined peripheral degenerative retinoschisis with retinal detachment and an encircling scleral buckle which had been placed two months earlier by the referring ophthalmologist. OCT confirmed both retinoschisis with small intraretinal cysts and retinal detachment with subretinal fluid in the macula, as well as an epiretinal membrane (Fig. 2A). The subretinal fluid extending temporally from the fovea and involving the inferior temporal quadrant corresponded with the posterior segment exam. Six months after pars plana vitrectomy, internal drainage of subretinal fluid, endolaser, and fluid gas exchange, the visual acuity had improved to 20/50 (Fig. 2B).

Figure 2. (A) Initial Examination of Case 2. A 62 Year-Old Woman, Best-Corrected Visual Acuity is 20/300 in the Left Eye. Left: Fundus Photograph of the Left Eye Showing Macular Schisis Combined with Retinal Detachment Extending Temporally from the Fovea. Both Inner and Outer Layer Holes are Evident to the Right of the Fovea. Right: OCT of the Left Eye Showing Retinal Detachment Involving the Macula. Subretinal Fluid Can be Seen Below the Fovea and Extending Temporally Corresponding to the Fundus Photograph. (B) Left: Post-Operative Montage Photograph of Left Eye Showing Retinal Reattachment. Right: OCT Through Fovea Showing a Normal Contour After Surgery.

Case 3

A 52-year-old man was referred with a history of progressive decrease in vision in the left eye for 2 months. His best corrected visual acuity was 20/20 in the right eye and 20/25 in the left eye. The left eye showed a large degenerative retinoschisis cavity involving the superior temporal quadrant and extending into the superior foveal edge (Fig. 3A). Peripherally there were 3 large outer wall breaks in the retinoschisis cavity superior temporal to the macula. In addition, there were 2 small inner wall breaks inside the temporal arcade. The patient also had a small amount of hemorrhage within the schisis cavity which demarcated the inferior border of the schisis. The OCT confirmed the presence of retinoschisis and retinal detachment extending from the periphery posteriorly to a rolled edge of the inner retinal layer (Fig. 3A). The patient underwent combined pars plana vitrectomy, scleral buckling, fluid gas exchange and endolaser. A chorioretinal scar (Fig. 3B) remained in the previous retinoschisis area. Final visual acuity was 5/200 secondary to macular distortion.

Figure 3. (A) Left: Montage Photograph of Case 3 Showing the Superior Temporal Retinoschisis Extending to the Foveal Edge. Right: OCT of the Left Eye Showing Combined Retinoschisis and Retinal Detachment. To the Right of the Fovea and Extending into the Temporal Quadrant There is Subretinal Fluid Corresponding to the Retinal Detachment. (B) Left: Postoperative Montage Photograph of the Left Eye Showing a Flat Retina with Chorioretinal Scarring and an Encircling Scleral Buckle. Right: OCT Horizontal Cross Section Through the Fovea of the Left Eye Confirming Retinal Reattachment with Residual Macular Edema.

Case 4

A 37-year-old woman noted distorted vision RE for 1 year prior to referral. Visual acuity with best correction was RE 20/70 and LE 20/15. Degenerative Retinoschisis and concurrent retinal detachment extending into the macula were diagnosed. Multiple large outer layer retinal breaks were identified (Fig. 4A). The OCT showed subretinal fluid extending under the fovea. The patient underwent pars plana vitrectomy, scleral buckling surgery, endolaser treatment, and fluid gas exchange RE. At the 13 month follow-up examination, visual acuity in the RE was 20/30 and complete retinal reattachment was maintained (Fig. 4B).

Figure 4. (A) Left: Montage Photography of Case 4 Showing Temporal Retinoschisis and Retinal Detachment Extending into the Macula. Right: OCT of the RE Shows Retinal Detachment Extending Beneath the Fovea. The Retinoschisis Component is not Seen in this Image. (B) The Postoperative Montage Photographs Show Complete Retinal Reattachment with Chorioretinal Scaring from the Laser Treatment to Large Outer Wall Holes. The Postoperative OCT Returned to Normal.

Discussion

Degenerative retinoschisis in the absence of retinal detachment is generally managed with serial observation. OCT has been used to differentiate more peripheral degenerative retinoschisis from retinal detachment.³ It is important from a preoperative standpoint to assess for both the presence and extent of retinal detachment, and degenerative retinoschisis.

Other ancillary tests employed to make the distinction between retinoschisis and retinal detachment include visual field testing, indirect ophthalmoscope perimetry, laser photocoagulation, and B-scan echography with or without scleral indentation.^4–7 In the assessment of retinal detachment versus retinoschisis, there are major limitations using these tests. These include the invasive and non-definitive nature of laser photocoagulation, the difficulty in assessing visual field in cases of more anterior pathology, the subjective nature of indirect ophthalmoscope perimetry, and the inability to differentiate between the two in cases of highly elevated detachments using echography.^4–7

In this series, the OCT appearance of retinoschisis in cases combined with retinal detachment was variable. One patient had a complete split between the inner and outer retina resulting in a “rolled under” outer retina layer. Other patients showed outer wall holes in retinoschisis and subretinal fluid extending beneath the fovea. In the preoperative assessment of patients with combined retinoschisis-retinal detachment, OCT may help identify and document full-thickness retinal detachment as well as the typical splitting in degenerative retinoschisis.