Peter Good

Pigmentary retinal dystrophy and the syndrome of maternally inherited diabetes and deafness caused by the mitochondrial DNA 3243 tRNALeu A to G mutation1

OBJECTIVE To study the association of retinal disease and the syndrome of maternally inherited diabetes and deafness caused by an A to G mutation in the tRNA leucine gene at base pair 3243 (A3243G) of the mitochondrial genome. DESIGN Observational study of a genetically defined subject group. PARTICIPANTS Thirteen subjects with the mitochondrial DNA A3243G mutation from seven different pedigrees with maternally inherited diabetes and deafness. INTERVENTION Assessment of visual symptoms and visual acuity, dilated indirect ophthalmoscopy, retinal photography, and retinal electrophysiology. MAIN OUTCOME MEASURES Loss of vision, funduscopic evidence of pigmentary retinal disease or diabetic retinopathy, and electrophysiologic evidence of defective functioning of the retinal pigment epithelium/photoreceptor complex. RESULTS Funduscopic examination revealed abnormalities of retinal pigmentation in ten subjects (77%). Defects included speckled and patchy hyperpigmentation at the posterior pole of the fundus, particularly in the macular area, and varying degrees of loss of retinal pigmentation. Three subjects (23%) had visual symptoms, which included night blindness, visual loss, and photophobia. Electrophysiologic studies revealed impaired electro-oculogram responses in four of nine subjects with defects of retinal pigmentation (44%), two of whom also had much reduced scotopic and, to a lesser extent, flicker electroretinogram b wave potentials. Two subjects had diabetic retinopathy, including one with retinal depigmentation and impaired electro-oculogram activity. Both subjects with diabetic retinopathy had unilateral reduced electroretinogram responses, especially oscillatory potentials. CONCLUSIONS Abnormalities of retinal pigmentation are common in subjects with maternally inherited diabetes and deafness caused by the mitochondrial DNA A3243G mutation. Visual symptoms, in particular loss of visual acuity, appear to be infrequent. The combination of deficits in the electro-oculogram and scotopic and flicker electroretinograms suggests that the retinal dystrophy includes defective functioning of retinal pigment epithelial cells and of both rod and cone photoreceptors. The pigmentary retinopathy does not prevent diabetic retinopathy; a single subject had funduscopic and electrophysiologic evidence of both diseases. Current evidence suggests that the mitochondrial DNA A3243G mutation accounts for 0.5% to 2.8% of diabetes. Most ophthalmic and diabetic clinics are therefore likely to contain such patients, who may benefit from identification of the genetic defect causing their disease and from genetic counseling.

Micro syndrome in Muslim Pakistan children

OBJECTIVE To date, Micro syndrome has been reported in only three children from one family. We describe an additional 14 children from 11 families. DESIGN Retrospective case series. PARTICIPANTS Fourteen children from 11 families attending one of five British hospitals. MAIN OUTCOME MEASURES The following features were documented: pre- and postoperative eye findings, electrophysiologic analysis, systemic abnormalities, development, neuroimaging, genealogy, geographic origin of family. RESULTS We expand and modify the description of ocular and electrophysiologic findings in Micro syndrome. The eye findings of microphakia, microphthalmos, characteristic lens opacity, and atonic pupils were the presenting feature in all infants and were the most reliable diagnostic signs in the immediate postnatal period. Cortical visual impairment, microcephaly, and developmental delay were not always detectable initially; they developed in all children by 6 months of age. Microgenitalia were a useful diagnostic clue in affected males only. Therefore, eye features were more consistently useful in determining diagnosis than dysmorphology or brain imaging. The families of all the children originate from the Muslim population of Northern Pakistan. Inheritance is likely to be autosomal recessive. CONCLUSIONS Micro syndrome usually presents to the ophthalmologist, who may be able to make the diagnosis on the basis of characteristic eye findings combined with ethnic origin. Initially, the nature and severity of nonophthalmic features are not apparent. Early diagnosis of the underlying condition is important to guide management of the cataracts, glaucoma, and developmental delay. It is helpful for the family and medical staff to be aware of the low level of vision that develops despite optimal ophthalmic intervention. Genetic counseling extending into the wider family is particularly important in view of the high rate of consanguinity.

High resolution Optical Coherence Tomography demonstration of membranes spanning optic disc pits and colobomas.

Objectives: To demonstrate the features of optic disc pits and colobomas revealed by high-resolution optical coherence tomography (OCT) and their association with the development of maculopathy. Methods: Subjects with disc pits or colobomas and no other ocular history underwent full ophthalmic examinations including logMAR visual acuity and contrast sensitivity. Fundus photographs and high-resolution OCT images were obtained. Results: Seven patients were identified with optic disc pits or colobomas aged 25 to 63 years. Five patients had a unilateral optic disc pit, one had a unilateral disc coloboma, and another had bilateral disc colobomas. Apart from one eye with a grossly anomalous disc, vision was logMAR 0.4 or better in all eyes. In three of five eyes without maculopathy, a complete membrane could be identified traversing the optic disc cup that was absent or deficient in the three eyes with maculopathy. One patient with optic disc pit and marked schisis-like separation of the retinal layers throughout the macula was asymptomatic with logMAR visual acuity of 0.0 and normal achromatic contrast sensitivity. Conclusions: In this small series of patients with optic disc pits or colobomas, it was possible to identify a membrane spanning the optic disc cup, and it is speculated that this may protect against the development of maculopathy. Schisis-like separation of retinal layers can be associated with normal visual function.

Visual Outcomes after Blunt Ocular Trauma

OBJECTIVE To describe the prognosis and retinal location in patients presenting with acute traumatic maculopathy and extramacular retinal injuries. DESIGN Retrospective, noninterventional case series. PARTICIPANTS AND CONTROLS All patients presenting with commotio retinae or sclopetaria retinae to the Birmingham Midland Eye Centre Eye Casualty from October 1, 2007, to February 23, 2011. METHODS The notes of all patients presenting with ocular trauma in the specified time period were examined to identify suitable patients and demographic and injury data were extracted. MAIN OUTCOME MEASURES Outcome was assessed by visual acuity (VA). RESULTS For macular commotio retinae, 53 patients were identified, of whom 34 had adequate follow-up to determine final VA. The median presenting VA was 20/40; 25 patients (74%) recovered to ≥ 20/30. The median extent of visual recovery was 0.18 logarithm of the minimum angle of resolution (logMAR). For extramacular commotio retinae, 117 patients were identified, of whom 58 had adequate follow-up to determine final VA. The median presenting VA retinae was 20/30; 55 patients (95%) recovered to ≥ 20/30. The median extent of visual recovery was logMAR 0.076. There was 1 case of extramacular sclopetaria retinae. The 3 most common retinal locations of extramacular commotio retinae, in order of frequency, were inferotemporal (37%), temporal (17%), and superotemporal (17%); <5% of cases were in a nasal location. CONCLUSIONS This is the first report on the prognosis of acute traumatic maculopathy and extramacular commotio retinae. After macular injury, 26% of patients were left with a VA of ≤ 20/30, although the proportion with visual impairment is higher than this because (1) a deterioration from 20/15 to 20/30 is significant to many patients; and (2) additional patients are visually impaired by symptomatic paracentral visual field defects despite a normal VA. Reduced VA after extramacular commotio retinae may represent occult macular injury or previously undiagnosed visual impairment in the affected eye. Extramacular commotio occurs mostly in an inferotemporal to temporal location, consistent with direct trauma to the sclera overlying the injured retina. FINANCIAL DISCLOSURE(S) The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Neuroretinal cell death in a murine model of closed globe injury: pathological and functional characterization.

PURPOSE Blunt ocular trauma causes severe retinal injury with death of neuroretinal tissue, scarring, and permanent visual loss. The mechanisms of cell death are not known, and there are no therapeutic interventions that improve visual outcome. We aimed to study the extent, distribution, and functional consequences of cell death by developing and characterizing a rat model of retinal injury caused by blunt ocular trauma. METHODS The eyes of anesthetized adult rats were injured by either weight drop or low-velocity ballistic trauma and assessed by clinical examination, electroretinography, light microscopy, electron microscopy, and TUNEL. Projectile velocity was measured and standardized. RESULTS Weight drop did not cause reproducible retinal injury, and the energy threshold for retinal injury was similar to that for rupture. Low-velocity ballistic trauma to the inferior sclera created a reproducible retinal injury, with central sclopetaria retinae, retinal necrosis, and surrounding commotio retinae with specific photoreceptor cell death and sparing of cells in the other retinal layers. The extent of photoreceptor cell death declined and necrosis progressed to apoptosis with increasing distance from the impact site. CONCLUSIONS This is the only murine model of closed globe injury and the only model of retinal trauma with specific photoreceptor cell death. The clinical appearance mirrors that in severe retinal injury after blunt ocular trauma in humans, and the ultrastructural features are consistent with human and animal studies of commotio retinae. After ocular trauma, photoreceptor apoptosis may be prevented and visual outcomes improved by blocking of the cell death pathways.

Does use of isotretinoin rule out a career in flying

Aim: To evaluate whether previous isotretinoin use induces permanent, measurable, and clinically significant abnormalities in night vision such that flying is precluded, and whether potential military and civilian commercial aviators should be screened routinely. Methods: A retrospective, non-interventional, consecutive case series of 47 individuals with a confirmed history of oral isotretinoin use were compared to 20 age and sex matched controls. Results: 47 individuals (44 males and three females), age range 17–33, underwent Goldmann-Weekers dark adaptation (DA) and standard electroretinogram (ERG) according to ISCEV protocols. 34 patients showed no abnormality in any parameters. Two patients had abnormal DA and ERGs. The mean scotopic ERG b wave amplitude of the isotretinoin group was 496.5 μV (SD 51.3 μV) compared with 501.7 μV (62.3.1 μV) among the controls. The group mean a:b ratio was 0.55 (0.04) compared to 0.69 (0.08) in the controls. Conclusion: Previous use of isotretinoin may have caused retinal toxicity in two subjects and laboratory evidence of night blindness in 11 further subjects. One subject had subclinical changes remaining in the ERG 96 months after cessation of isotretinoin. This may justify the directed use of electrophysiological screening in professions that are night vision critical.

A Case of Severe Hydroxychloroquine-Induced Retinal Toxicity in a Patient with Recent Onset of Renal Impairment: A Review of the Literature on the Use of Hydroxychloroquine in Renal Impairment

We present a case of a 67-year-old female who presented with a twelve-month history of progressive blurred vision in both eyes. The patient was on hydroxychloroquine 200 mg twice a day for eight years for the treatment of scarring alopecia. Two years prior to presenting, the patient was found to have chronic kidney disease stage 3 secondary to hypertension. Examination revealed bilateral reduced visual acuities with attenuated arterioles and pigmentary changes on retinal assessment. Goldmann visual fields showed grossly constricted fields in both eyes. The patient was diagnosed with retinal toxicity secondary to hydroxychloroquine probably potentiated by renal impairment. Risk factors for retinal toxicity secondary to hydroxychloroquine can be broadly divided into dose-related and patient-related factors. Our patient developed severe retinal toxicity despite being on the recommended daily dose (400 mg per day). Although retinal toxicity at this dose has been documented, the development of renal impairment without dose adjustment or close monitoring of visual function is likely to have potentiated retinal toxicity. This case highlights the need to monitor renal function in patients on hydroxychloroquine. Should renal impairment develop, either the drug should be stopped or the dose reduced with close monitoring of visual function by an ophthalmologist.