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Clinical Persistent hyaloid arteries Kirit Patel describes two cases where previous sight loss in one eye made the prognosis in the other all the more critical A Figure 1 Left eye corneal scarring and complete vascularisation 35-year-old insulin dependent diabetic patient from Nigeria was advised by her sister to have a thorough eye examination. Her sister was concerned that she needed thick glasses and a magnifier to read. Her sister, who was six years older and one of our patients, also suffered from diabetes and was very diligent in controlling her sugar level. The patient had lost her right eye 10 years ago following a corneal infection but she could not remember exactly the cause. Over the past 10-12 years she had undergone numerous laser treatments and a successful aphakic cataract operation. Both eyes had trabeculectomy operations for glaucoma and the left eye was treated with topical Alphagan eye drops as well as Maxitrol steroid eye drops when necessary. Figure 2 Greyish white fibrous membrane indicating previous new vessels well as cotton-wool spot ● Right optic disc had greyish white fibrous membrane indicating previous new vessels on the disc (Figure 2) ● Right temporal retina revealed a much larger fibrous membrane and a much smaller membrane on the nasal aspect as well – again remnants of previous new vessels on the retina ● There were numerous occluded retinal veins showing cattle track blood flow ● Inferior branch retinal artery showing possible occlusion and calibre change. ● The retina had pan-retinal photocoagulation and remnants of laser scars. Decision taken The patient was told that owing to the loss of the left eye she could not Spectacle prescription R +11.00DS / -1.00DC X 180 VA 6/36 Add +4.00DS VA N24. L no light perception. Ocular findings ● Bilateral intraocular pressures were 22mmHg ● Left eye corneal scarring and complete vascularisation – no fundus view possible (Figure 1) ● Right eye cataract extraction and no intraocular implant (aphakia) ● Right eye revealed R1 retinopathy consisting of a few haemorrhages as 30 | Optician | 15.10.10 be prescribed an intraocular lens or a contact lens and her only choice was a lenticular spectacle lens for distance and reading. She was also prescribed a magnifier for reading. In this patient’s case the new vessels regressed following treatment and the regression of the new vessels led to a fibrous tissue which was noticed on the disc and elsewhere on the retina. It was unfortunate that she lost her sight due to poor diabetes control in her younger days. How often do we see young diabetics losing their sight and in some cases suffering from strokes or cardiac problems due to their poor compliance with instructions? Case 2 Persistent hyaloid artery and hyaloid membrane A 76-year-old Russian patient came for his routine diabetic assessment. He recalled losing the sight in his right eye following a karate kick some time in his youth. He had cataract in his left eye and had had a right cataract extraction some 20 years ago. For his diabetes he took metformin and vitamins A, C and E plus bilberry. Spectacle prescription R count fingers in outside corner. L -8.75DS / -1.00DC X 40 VA 6/12 and N5 (without specs). Figure 3 Right vitreous shows the hyaloids membrane behind the implant Ocular findings ● Right eye pseudo-aphakia and opticianonline.net Clinical Figure 4 The hyaloid artery has a central portion and two extended arms intraocular implant ● Right vitreous shows the hyaloid membrane clearly behind the implant. This is seen as central triangular membrane and another less clear membrane on the left to this triangular piece (Figure 3) ● Right fundus shows a persistent hyaloid artery extending from the optic disc. A shiny white bright image is due to the hyaloid membrane which we observed on the anterior imaging ● The hyaloid artery is seen in much greater detail using the retinal assessment module (RAM) which shows the membrane much more clearly. The hyaloid artery has a central portion and two arms extending from it (Figure 4) ● The chorioretinal scarring inferior to the disc is also evident and this could be related to the myopia or it could be related to the trauma following the karate kick ● Macula appears unclear ● Right and left eye showing R0 retinopathy and intraocular pressures within normal range of 14mmHg in the right eye and 16mmHg in the left eye ● Left eye early posterior subcapsular cataract ● Left myopic disc with chorioretinal changes surrounding ● The left disc appears fairly cupped and suspect especially when we view the veins superiorly and inferiorly bayoneting the edge of the cup ● Left maculr epiretinal membrane (Figure 5). Decision taken The patient was reassured that he had no diabetic retinopathy in either eye and his right eye could have been lost due to myopia or it could have been the karate kick and the cataract that ensued 32 | Optician | 15.10.10 Figure 5 OCT scan of macular area would have been traumatic. The left eye cataract was in the early stages so no intervention was necessary. The patient was coping well with his high myopic correction and without for reading. His optic disc cupping was suspect so it was suggested that he had visual field test and nerve fibre analysis to eliminate glaucoma. The epiretinal membrane was light and there were no reasons to expect problems in the future. Discussion The hyaloid artery is a branch of the ophthalmic artery which extends from the optic disc through the vitreous humour and to the lens at the front. This artery supplies nutrients to the lens in the growing foetus. In the 10th week of embryological development the lens starts to grow independently and the hyaloid artery regresses while its proximal portion remains as the central artery of the retina. The regression of the hyaloid artery creates a clear zone through the vitreous called the Cloquet’s or hyaloid canal. In some patients the hyaloid artery may not regress fully and the remnant is called persistent hyaloid artery. The anterior hyaloid membrane seen is a layer of collagen separating the anterior vitreous from the crystalline lens. The posterior hyaloid membrane separates the retina from the vitreous. Hence the hyaloid membrane is a Figure 6 Hyaloid membrane detachment thin, delicate coat that runs from the pars plana to the posterior surface of the crystalline lens. The posterior hyaloid membrane is close to the inner limiting membrane of the retina and it is common to see posterior hyaloid membrane detachment occurring with a ring of Weiss representing full posterior vitreous detachment or peri-foveal vitreous detachment (Figure 6 shows a hyaloid membrane detachment – author has named this as a pseudo operculum). Useful reading 1 Andres B, Jean-Marie Parel, Fabrice Manns. Evidence for posterior zonular fiber attachment on the anterior hyaloid membrane. Investigative Ophthalmology and Visual Science 2006, 47, 4708-4713. 2 Foos RY. Posterior vitreous detachment. Trans Am Acad Ophthalmol Otolaryngol 1972; 76: 480. 3 Heegaard S. Structure of the human vitreoretinal border region. Ophthalmolgica 1994; 208: 82-91. 4 Snead MP, Snead DRJ, Mahmood A, Scott JD. Vitreous detachment and the posterior hyaloid membrane: a clinicopathological study. Eye, 1994; 8: 204-209. 5 Streeten BW. The zonular insertion; a scanning electron microscopic study. Invest Ophthalmol Vis Sci, 1977;16:364–375. ● Kirit Patel practises in Radlett, Herts opticianonline.net