Optic nerve head pit pit, Optic pit

DESCRIPTION An head pit is a congeni- tal condition, but one that may be associated with degenerative compli- cations. The pit develops as an anoma- lous outpouching of neuroectoderm, surrounded by a connective tissue capsule that communicates with the subarachnoid space. Larger and more temporally located pits carry a substan- tial risk of non-rhegmatogenous serous retinal and macular detachment. Temporal optic disc pit associated with serous Scanning laser tomography map (right) showing 0.8mm deep extending to the macula pit extending infero-temporally to the disc rim, with associated SYMPTOMS supero-temporal defect (left) Optic nerve head pits are asympto- matic in the absence of macular retinal DIFFERENTIAL DIAGNOSIS show resolution of subretinal fluid detachment. When this complica- Central serous chorioretinopathy, other following surgery to alleviate vitre- tion occurs – usually in the third or optic nerve dysplasias – , oretinal traction. Procedures including fourth decade – potential symptoms Morning glory syndrome, Normal pars plana and intraocular include metamorphopsia (distortion of tension glaucoma. As with other gas tamponade have been employed. objects), micropsia (objects appearing congenital optic disc malformations, However, even with full resolution small) and blurred vision. the disc diameter is larger in an optic of retinal detachment, vision will not disc pit, whereas glaucoma being an necessarily improve. SIGNS acquired condition tends to have a ● At the optic disc, there is a pale, round similar overall disc diameter in the two Prognosis or oval pit of variable size. The pit is eyes. Serous retinal detachment has a poor typically discoloured; it may be pale, prognosis, with over half of affected yellowish or grey. More than 80 per SEE ALSO eyes having acuity of 20/100 (6/30) or cent of cases are unilateral and the optic Retinal detachment, Macular hole. worse within one year. disc is larger in the affected eye ● Visual field defects – most commonly MANAGEMENT Review and advice arcuate – are present in 60 Yearly review is recommended in the per cent of cases, particularly when Additional investigations absence of complications. The patient neuroretinal rim tissue is affected With fluorescein angiography, the pit may be given an Amsler grid for self- ● If the optic disc pit is centrally located, usually demonstrates early hypofluo- monitoring and educated regarding then glaucoma is an important differ- rescence and late hyperfluorescence. macular detachment symptoms. ential diagnosis Scanning laser may ● When the pit is located temporally, assist in evaluating the pit configu- The full series of these articles will be available in the as in around two-thirds of cases, there ration. Visual field assessment is book Posterior Eye Disease and Glaucoma A-Z by Bruce is a 40 to 50 per cent chance of devel- indicated. AS, O’Day J, McKay D and Swann P. £39.99. For further oping serous retinal detachment at information click on the Bookstore at opticianonline.net the macula. The retinal detachment Laser surgery appears as a smooth elevation of the The natural course of serous macular ● Adrian Bruce is a Chief Optometrist at the Victorian extending from the optic disc pit detachment carries a poor prognosis, College of Optometry and a Senior Fellow, Department towards the macula. In about 25 per due to permanent macular damage; of Optometry and Vision Sciences, The University of cent of eyes with retinal detachment unfortunately there is little evidence Melbourne. a lamellar, outer layer macular hole that existing treatments are beneficial. ● Justin O’Day is an Associate Professor in the develops. Some practitioners prefer to intervene Department of Ophthalmology, The University of when signs of detachment first appear. Melbourne and Head Of Neuro-Ophthalmology Clinic, Prevalence Laser photocoagulation to the temporal Royal Victorian Eye and Ear Hospital. Rare (about 1 in 10,000). margin of the optic disc may reduce the ● Daniel McKay is a Medical Officer at the Royal accumulation of subretinal fluid. Victorian Eye & Ear Hospital. SIGNIFICANCE ● Peter Swann is Associate Professor in the School of May cause severe, irreversible loss of Incisional surgery Optometry, Queensland University of Technology. central vision. Observations in several case studies opticianonline.net 16.11.07 | Optician | 55