A Case of Unilateral Retinitis Pigmentosa Associated with Full Thickness Macular Hole.

A 44-year-old Saudi female presented with poor right eye vision for 3 years. Visual acuity (VA) was 20/400 in the right eye and 20/20 in the left eye. Examination and imaging showed all the typical features of retinitis pigmentosa in the right eye associated with full thickness macular hole (FTMH) and an essentially normal left eye. The case underwent pars plana vitrectomy with internal limiting membrane peeling and gas tamponade that resulted in anatomical closure of the FTMH, but VA remained the same.

Introduction

Retinitis pigmentosa (RP) is a group of inherited disorders which are known by progressive visual dysfunction, cell loss, and finally atrophy of retinal tissue. It affects 1 in 3500–5000 people worldwide.[1] Over 40 genes have been associated with RP so far, with the majority of them expressed in either the photoreceptors or the retinal pigment epithelium.[2] Initial disturbance of photoreceptors causes subsequent damage to inner retinal cells.

RP is characterized by night blindness, visual field constriction followed by reduced central vision. The retinal lesions are characterized by intraretinal pigment migration, mainly in the peripheral retina, in addition to vascular attenuation and disc pallor. The macular area is usually spared from photoreceptor degeneration until late stages of the disease. However, during the disease, some macular changes have been observed in association with RP. The most frequently observed macular abnormalities are cystoid macular edema (CME) and macular holes (MHs).[34] Moreover, other vitreoretinal interface alterations, such as vitreous traction and epiretinal membranes, have been reported.[34]

Unilateral RP (URP) is an unusual form of presentation of the disease with reported incidence rate of up to 5% of all RP cases.[5] To diagnose the primitive URP, the Francois and Verriesr criteria are needed:[6]

Exclusion of all infective etiologies

Clinical signs of retinitis presented in the affected eye

No symptoms in the fellow eye

Long follow-up period (at least 5 years).

In previous studies, the prevalence of full thickness MH (FTMH) in RP patients was estimated between 0.5% and 0.6%.[37]

In this study, we report a case of URP associated with FTMH. We are not aware of previously reported case(s) of URP with FTMH in the same (affected) eye.

Case Report

A 44-year-old Saudi female presented to the retina clinic at the King Khaled Eye Specialist Hospital (KKESH) with a history of poor vision in the right eye discovered 3 years earlier. She had no family history of any eye problems. Her parents are not related (negative consanguinity), and none of her siblings (four brothers) is affected. She is medically free with no history of blood loss. She had no history of ocular inflammations, no history of ocular trauma, and no previous ocular surgeries. At the time of the first visit, the best-corrected visual acuity was 20/400 in the right eye and 20/20 in the left eye. Intraocular pressure was normal in both eyes. Slit lamp examination of the right eye showed very early posterior subcapsular cataract. Fundus examination of the right eye revealed intraretinal pigment migration in the midperiphery, waxy disc pallor, and vessel attenuation. Color fundus photographs were taken using wide field Optos fundus camera (Optos 200TX, Dunfermline, UK). The fundus appearance of the right eye is shown in Figure 1a. Examination of the left eye was essentially normal [Figure 1b].

Figure 1

Baseline assessment of both eyes in a case of unilateral retinitis pigmentosa. (a) Color photograph of the right eye showing midperipheral intraretinal pigment migration, pale disc, and blood vessels attenuation. (b) Color photograph of the left eye with normal fundus appearance. (c) Fundus autofluorescence of the right eye showing decreased autofluorescence signal in the midperiphery associated with an abnormal parafoveal ring. (d) Autofluorescence of the left eye showing normal appearance. (e) Optical coherence tomography of the right eye showing full thickness macular hole with intraretinal fluid around it. (f) Optical coherence tomography of the left eye with normal foveal contour. (g) Photopic response of the full-field electroretinogram. It shows very diminished responses from the right eye and normal responses from the left eye. (h) Scotopic response full-field electroretinogram. It shows flat recordings from the right eye and normal responses from the left eye

Fundus autofluorescence (FAF) imaging was done using wide field Optos system (Optos 200TX) with 488 nm wavelength. FAF of the right eye revealed decrease AF signal in the midperiphery associated with an abnormal parafoveal ring or curvilinear arc of increased AF [Figure 1c]. FAF of the left eye was normal [Figure 1d]. Retinal structure was analyzed qualitatively with transfoveal horizontal spectral domain optical coherence tomography scans (OCT, Heidelberg Engineering, Inc., Heidelberg, Germany). OCT of the right eye showed FTMH [Figure 1e]. The left macula appeared normal [Figure 1f].

Retinal function was evaluated with full-field electroretinography (ffERG, Nicolet Biomedical Instruments, Madison, Wisconsin, USA) in the dark-adapted and light-adapted state according to the International Society for Clinical Electrophysiology of Vision standards, with a few modifications as follows. Full-field electroretinograms were recorded in a Nicolet analysis system (Nicolet Biomedical Instruments, Madison, Wisconsin, USA), after dark adaptation of subjects for 40 min, dilatation of the pupils with topical cyclopentolate 1% and metaoxedrine 2.5% and topical anesthesia, with a Burian–Allen bipolar contact lens and a ground electrode applied to the forehead. Responses were obtained stimulating with single full-field flash (30 ms) with blue light (0.81 cd-s/m2: rod response) and with white light (10.02 cd-s/m2: combined rod-cone response). Photopic responses were obtained with a background illumination of 3.4 cd-s/m2 to saturate the rods.

The ffERG responses were markedly reduced in the right eye [Figure 1g], and it was normal in the left eye [Figure 1h].

We clinically diagnosed the case as URP. After consulting the Genetic Department in KKESH, they did not recommend genetic testing as this considered a sporadic case being the only affected case in the whole family. We counseled the patient and she agreed to proceed with right MH surgery in a trial to preserve her central vision in the affected eye with a low chance of improving central vision.

The patient underwent right 23-gauge pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling and gas tamponade (C3F8) that went uneventful. She was advised to posture face down for 5 days (12 h/day). One week postoperatively, the FTMH was closed [Figure 2c]. At her last follow-up (6 months postoperatively), the hole remained closed and visual acuity (VA) remained at the level of 20/400 [Figure 2]. Figure 2 a shows the post operative appearance of the case (a; color photo, b; AF image, and c; OCT appearance).

Figure 2

Postoperative imaging of the right (affected) eye. (a) Color fundus photograph of the right eye showing the typical retinitis pigmentosa features. (b) Fundus autofluorescence of the right eye showing decreased autofluorescence signal in the midperiphery associated with an abnormal parafoveal ring. (c) Optical coherence tomography of the right eye showing closed hole with atrophic changes

Discussion

While RP can be inherited as an autosomal dominant, autosomal recessive, or X-linked trait, sporadic cases have also been reported. URP is mostly sporadic and it appears in adult ages.[8]

Despite a large number of bilateral RP cases, the URP cases are rare. The rarity of URP has clarified the importance of electrofunctional examinations.[9] The case presented here conforms to the four proposed criteria to justify the presumptive URP. The case we present is unique because, despite the rare presentation of URP, the patient also has unilateral MH in the affected eye.

The mechanism of MH formation in RP cases is not fully understood. As a consequence of chronic blood–retinal barrier breakdown, which is reported to occur in 8%–50% of the instances, the inner surface of the retina may present irregularities of the ILM.[10] Macular cysts tend to be confluent in some cases and, in combination with ILM wrinkling, sometimes may lead to the formation of MH encompassing different stages (from I to IV according to Gass classification). MHs have been reported in 4%–8% of eyes with different shapes and stages.[11] Detection of these abnormalities is crucial because they can significantly reduce the central visual function in patients with RP whose peripheral visual function is already compromised by RP. The possibility of spontaneous resolution of an FTMH was once described in the literature,[11] but generally therapeutic approach based on vitrectomy is necessary. That is why PPV and gas tamponade with done in this case with closure of the hole. There was no much improvement in VA postoperatively, but perhaps this prevented further deterioration of foveal function of this case or might have improved parafoveal fixation.

This case highlights the importance of investigating macular abnormalities in cases of RP. This is to detect treatable pathologies such as FTMH and CME. Treating these macular pathologies helps maintain central vision in RP cases.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.