Sir,

Visual loss due to intra-retinal pathology is not generally expected to improve with the use of a pinhole, while it is expected so, for media opacities and refractive errors. We herein report a case where we noticed visual improvement with the use of a pinhole in the presence of a central artery occlusion and foveal sparing due to a cilioretinal vessel.

Case report

A 62-year-old male patient with type 2 diabetes and hypertension, presented to his optician at 3 hours after sudden onset of painless loss of vision in the LE. The visual acuity recorded at the optician was RE 6/6 and LE 6/12. He was noticed to have ‘contracted’ visual fields. The patient was referred to the Eye casualty, Princess Alexandra Eye Pavilion, Royal Infirmary, Edinburgh as a suspected case of central artery occlusion LE.

He was seen in the eye Casualty 4 h later when the vision in the LE had dropped to 3/60, N36. It was noticed that the vision improved with a pinhole to 6/6 in the LE. Three experienced ophthalmologists using different Snellen acuity charts independently verified this. There was a left afferent pupillary defect and fundus examination revealed a central retinal artery occlusion with a cilioretinal artery sparing the fovea (Figure 1a). Retinoscopy did not reveal any refractive error and no improvement was seen with the addition of plus lenses. A Humphrey’s 24-2 full threshold visual field test was done (Figure 2). The superior temporal quadrant adjacent to fixation was relatively spared while the remaining three quadrants showed a dense scotoma. Anterior chamber paracentesis was done under a slit-lamp. Intravenous acetazolamide was administered.

Figure 1
figure 1

(a) Retinal oedema due to central retinal artery occlusion, with cilio-retinal vessel sparing the fovea at day 2. (b) Retina oedema regressed well at day 12.

Full size image
Figure 2
figure 2

Sparing of upper temporal quadrant of the fovea.

Full size image

A fluorescein angiogram was done the following day. This revealed delayed arterial filling in the left eye. A cilioretinal artery supplying the foveal area was present and filled normally. On the 12th day, his unaided visual acuity in the LE had improved to be 6/6 and the retinal oedema had resolved (Figure 1b).

Comments

Improvement of vision is noticed with a pinhole in cases of refractive errors, and peripheral media opacities. Pinhole vision is not expected to improve in the presence of retinal pathology. In Central serous retinopathy (CSR), where the whole retina is lifted up, a relative hypermetropia occurs and improves with refractive (plus lenses) correction. It was unusual to notice visual improvement with a pinhole (but not with lenses) in our case. A literature search did not reveal any references to a similar occurrence. Considering the limited sparing of his central vision immediately after arterial occlusion, it is likely that the pinhole enabled him to direct the image onto the functioning quadrant of his retina, thereby obviating the distortion caused by part of the image falling on functioning retina and part on non-functioning retina. Improvement in unaided vision corresponded to resolution of retinal oedema. It is therefore likely that retinal oedema also contributed in some manner to the observed phenomenon.