Fissure, fluid, and functional loss

Case Report

A 15-year-old female presented with decreased vision in her left eye of 15 days duration. There was no history of any trauma to the eye, or any systemic or ocular disease in the past. The best-corrected visual acuity in her right eye was −0.25 sph = 6/5 and in the left eye was −0.50 sph = 3/60.

Slit lamp evaluation of the anterior segment and intraocular pressure recording was normal. Amsler chart showed a central scotoma in her left eye and was normal for the right eye. Fundus evaluation of the right eye was normal [Figure 1a]. Left eye fundus picture is given below [Figure 1b]. Optical coherence tomography (OCT) of the disc and macula [Figure 2a and b] and fundus fluorescein angiography [Figure 3a-c] was performed to confirm the diagnosis.

Figure 1.

(a) Fundus right eye. (b) Fundus left eye

Figure 2.

(a) Optical coherence tomogram macula - right eye. (b) Optical coherence tomogram macula - left eye

Figure 3.

(a) Fundus fluorescein angiography right eye. (b) Fundus fluorescein angiography left eye early phase. (c) Fundus fluorescein angiography left eye late phase

Questions

1. What is your diagnosis?

2. What is the etiopathogenesis of lesion on the optic nerve?

3. What are the likely visual field changes?

4. What are the likely findings of fundus fluorescein angiogram?

5. What is seen on the OCT in the picture [Figure 2b] provided:

   1. White arrow
   2. Red arrow
   3. Yellow arrow.

6. What is the best available treatment modality?

7. What ocular investigation is essential before the surgical intervention?

Text

Optic disc pits are rare, congenital excavation of the optic nerve head, secondary to incomplete closure of the superior end of the embryonic fissure. They were described initially by Weithe in 1882. They form part of a spectrum of congenital optic disc anomalies, including morning glory syndrome, juxtapapillary staphyloma, and optic nerve coloboma, and appear as small, hypopigmented, grayish, oval or round excavated depression in the optic nerve head. The estimated prevalence of optic pits is between 0.02% and 0.19%.[1] About 10–15% of optic disc pits are bilateral. They occur equally in both genders and often have a predilection for the temporal region of the optic disc.[1,2] Visual deterioration is either due to associated macular changes or to the development of maculopathy.[1,2,3,4,5] Histologically, optic disc pit represents a defect in the lamina cribrosa.[1,2,3,4,5,6]

Macular changes

Optic pits along the rim of the optic disc are most likely to lead to serous detachments of the retina, with associated full-thickness or laminar retinal holes, retinal pigment epithelium mottling, and general cystic changes.[2,3] The retinal detachments usually confined between the superior and inferior vascular arcades, are contiguous with the optic disc and have cystic and schisis-like spaces involving the inner retinal layers, while the outer retina may secondarily detach as fluid accumulates in the subretinal space.[2,3,4]

Subretinal fluid

It has not been established conclusively where the subretinal fluid originates from. Four hypothesis predominate, each with varying levels of supporting evidence: Posterior vitreous abnormalities like vitreomacular or vitreopapillary traction, cerebrospinal fluid leaks from the subarachnoid space; fluid conduction through Bruch's membrane and the retinal pigment epithelium, and leak from immature or unsupported vessels within the optic disc pit.[1,2,3,4,5]

Diagnosis of optic pits can be made on a slit lamp funduscopic exam or with direct or indirect ophthalmoscopy. Ancillary tests like visual field charting, optical coherence tomogram, fundus fluorescein angiogram aid in confirming the diagnosis.[1,2,3,4,5]

Visual field testing

Visual field changes, which can be due to one or both of the following mechanisms:

1. A large optic pit may produce an arcuate scotoma or an enlarged blind spot.

2. Central scotoma due to associated maculopathy.[1,2,3,4,5]

Optical coherence tomography

Optical coherence tomography of an optic pit shows schisis like the separation between the inner and outer retina. Anomalies on the optic nerve head like – remnants of internal limiting membrane (inner limiting membrane of Elsching), connections between subretinal, and intraretinal space, perineural space, and the vitreous cavity, fluid spaces within the optic disc, may also be delineated.[2,3]

Fluorescein angiography

Fluorescein angiography is usually unremarkable in cases of the optic pit. There is no dye accumulation in the area of the serous detachment, although there may be late hyperfluorescence of the optic pit.[1,2,3,4,5]

Electrophysiology

Ill-defined and low-amplitude waveforms, consistent with schisis and serous detachment may be noted on electroretinography (ERG) and are helpful in the preoperative evaluation of macular function. Visual improvement is poor in patients with a poor ERG response even after anatomical reattachment.[1,2,3,4,5]

Treatment

There is no clear consensus about the best treatment available for the maculopathy with optic pits, as the prevalence of the condition is as rare as 1 in 11,000 patients and also because the studies examining this topic tend to be small, retrospective, noncomparative, and nonrandomized. Novel techniques such as triple treatment, employing vitrectomy, laser, and gas (with or without posterior hyaloid dissection), have been found to show promise, but requires confirmation in the future.[3,4,5]

Answers

1. Optic pit with associated serous macular detachment with retinoschisis.

2. The pit is thought to arise from incomplete closure of the superior end of the embryonic fissure.

3. Visual Field can be due to one or both of the following:

   1. An arcuate scotoma or may lead to an enlarged blind spot due to a large pit.
   2. Central scotoma due to associated maculopathy.

4. No dye accumulation in the area of the serous detachment. Late hyperfluorescence of the optic pit.

5. Optical coherence tomography [Figure 2b] macula and optic disc showing sensory retinal detachment with schisis of the retina at the fovea.

   1. White arrow - internal limiting membrane of Elschnig
   2. Red arrow - interneural space connecting with retinal schisis cavities
   3. Yellow arrow - optic pit connection with potential space causing sensory retinal detachment.

6. Pars plana vitrectomy, endolaser, and tamponade (with or without posterior hyaloid dissection).

7. Electroretinogram.