A Case of an Optic Pit

Abstract Optic pits can be congenital or acquired in nature. Congenital pits are typically temporal and round in shape. Recently, it has been reported that acquired optic pits are commonly found in eyes with pathological myopia.

I. Case History Patient HF was a pleasant 9-year-old African American female that presented complaining of blurry vision in the left eye. She denied headaches or double vision. Her mother reported that HF saw an ophthalmologist at a community health center earlier in the year where she was given glasses that HF lost 2 months ago. She had no pertinent medical history or family history, was not taking any medications, and has no known drug allergies.

II. Pertinent findings A full comprehensive eye exam was completed on HF. Her uncorrected presenting visual acuities were 20/25 OD and 20/400 at 40cm OS in the distance and 20/20 OD and 4/200 OS at near. Pinhole testing showed no improvement in the left eye. Gross examination revealed a large sensory angle esotropia and hypertropia in the left eye. We were unable to measure the magnitude deviation as the eye was constantly drifting and wasn’t able to fixate a target for cover test. The left esotropia and hypertropia were confirmed with Bruckner testing. Her pupils were both equal, round and reactive to light with no APD noted. EOMs were full in the right eye, and there was some over action of the medial rectus in the left eye. HF failed global and local stereopsis testing. The right eye was refracted to -0.50DS and the corrected visual acuity was 20/20 OD. No retinoscopy reflex was seen OS during static retinoscopy and refraction was not possible in the dry state. The potential acuity was measured with interferometry. HF could see the 20/25 target OD and was unable to see the 20/400 target OS. Anterior segment examination was unremarkable in both eyes. IOP was measured at 4:00PM using iCare, which measured 16 mmHg OD and 16 mmHg OS. The patient was dilated with cyclopentolate 1% OU (2 drops, 5 minutes apart) and phenylephrine 2.5% OU.

A cycloplegic retinoscopy OU revealed a refractive error of -0.50DS OD and -19.50 DS OS. The prescription was trial framed and the acuity in the left eye did not improve. Dilated fundus exam of the right eye revealed a healthy, round optic nerve head with a 0.25 H&V C/D ratio, a flat macula with a positive reflex, and normal vessels and periphery. Dilated examination of the left eye revealed a clear vitreous, a temporal optic disc pit, a nasal staphyloma, a flat macula with no foveal reflex, a tesselated fundus, normal vessels, lattice inferior and temporally, and white without pressure superiorly. Fundus photos were taken of both eyes at this visit. The optic nerve head in the left eye was noticeably larger than the optic nerve head of the right eye.

III. Differential diagnosis The diagnosis included pathological myopia of the left eye, an optic disc pit of the left eye, sensory esotropia and hypertropia of the left eye, and severe amblyopia of the left eye. We could not determine if the optic pit was congenital or acquired as there are no previous records for HF. An OCT of both eyes was performed 1 week after the initial visit to investigate the possibility of any retinal detachments. Since HF’s fixation with her left eye was unstable, OCT testing was unattainable.

IV. Diagnosis and discussion Optic pits are typically congenital or occur secondary to advanced glaucoma, but they can be acquired in cases of pathological myopia [1]. Georgalas et al reported that 85% to 90% of congenital optic disc pits are at the temporal optic disc, such as with patient HF, but the presence of pathological myopia could indicate that the pit was acquired in nature [2]. It is hypothesized that the mechanical stretching of the lamina cribosa in highly myopic eyes leads to the development of the optic pits [1].

Matsui et al evaluated the incidence between optic nerve pits in pathologically myopic patients in 2012 [1]. In the population of 198 highly myopic eyes examined, they reported that optic pits were as prevalent as 16.2% of cases [1]. 34.4% of them were optic disc pits, and 68.8% were conus pits [1]. When looking at their data, the researchers found that those with optic disc pits were more highly myopic and had significantly longer axial lengths than those who were highly myopic without any optic pits [1].

There are also many factors of HF’s optic disc that are typical of a congenital optic disc. Apart from the majority of congenital pits developing at the temporal margin of the disc, they also tend be round in shape [2]. In the cases of acquired pits, Matsui et al reported that they were triangular in shape [1]. Congenital optic pits also tend to be associated with optic nerve head megalodiscs, which can be seen in HF’s case [1]. An OCT of the optic pit would help with the differential diagnosis, as congenital pits tend to have a membrane that spans over the optic pit and those that are acquired do not [1].

V. Treatment, management The most appropriate treatment option for patient HF is optical correction of the left eye to try and improve the best-corrected visual acuity. Glasses were recommended for correction and for eye protection. The goal is to split the high prescription between the contact lenses and the glasses in order to increase comfort, cosmesis, and patient acceptance of the spectacle correction. We also recommended a retinal consult from Ophthalmology.

VI. Conclusion When optic pits develop in the temporal area of the optic nerve they can severely reduce the visual acuity in that eye. It is possible that acquired optic nerve pits are associated with pathological myopia, and clinicians should be aware of this relationship. OCTs are important in order to determine if there are any associated retinal detachments present.

1. Ohno-Matsui, K., Akiba, M., Moriyama, M., Shimada, N., Ishibashi, T., Tokoro, T., & Spaide, R. F. (2012). Acquired optic nerve and peripapillary pits in pathologic myopia. Ophthalmology, 119(8), 1685-1692. 2. Georgalas, I., Ladas, I., Georgopoulos, G., & Petrou, P. (2011). Optic disc pit: a review. Graefe's Archive for Clinical and Experimental Ophthalmology, 249(8), 1113- 1122. Imaging included in this case: Fundus photos OU