LOSS OF VISION
Temporary loss of vision and stroke risk
Transient ischaemic attacks (TIA) often precede a full episode of stroke. Recognition of patients having TIA symptoms can enable effective treatment. The clinical signs and symptoms of TIA include visual loss in one or both eyes lasting seconds to hours. The combined hazard ratio involving full or partial visual loss for stroke in a study of over 30,000 subjects aged 45 years and over was 0.29. The study method included subjects having temporary visual loss from any cause, including that due to migraine aura. Migraine is estimated to affect approximately six per cent of males and 17 per cent of females. If these cases were eliminated from the study, the hazard ratio for subsequent stroke from other causes could be considerably higher. Although urgent referral to a physician is necessary for any patient having visual loss not already under management, it may be helpful to eliminate migraine and retinal vascular occlusions from these alternatives.
Kleindorfer D, Judd S, Howard VJ, McClure L, Staffford MM, Cushman M, Rhodes D et al. Self-reported stroke symptoms without a prior diagnosis of stroke or transient ischemic attack: a powerful new risk factor for stroke. Stroke 2011; 42: 3122–3126.
Through a druse darkly
Nyctalopia is a relatively rare condition in which the subject has defective dark adaptation. It is associated with retinitis pigmentosa, vitamin A deficiency, high myopia and congenital abnormalities of the retinal rods. These conditions are bilateral with perhaps minor degrees of difference between the two eyes. A case report describes a 38-year-old woman who presented with a history of nyctalopia in the left eye only. Visual acuity, visual fields, colour vision and pupil reactions were normal in both eyes and magnetic resonance imaging and laboratory blood tests were all within normal limits. Fundus examination was unremarkable except for drusen on the superonasal disc margin and anomalous branching at the disc margin. This report appears to be the first to report unilateral nyctalopia. The cause of optic disc drusen is unknown but it is usually assumed to result from altered axoplasmic flow at the disc, which in this case may have damaged rod receptors in the peripheral retina.
Goh YW, Buller A. Do optic disc drusen cause unilateral nyctalopia? Case Report Ophthalmol 2011; 1: 77–79.
Sudden visual loss to frown over
A 32-year-old man underwent an injection of fatty tissue into his forehead to eliminate frown lines. The procedure was carried out under local anaesthesia with tissue harvested from the patient. During the procedure, the patient noted periocular pain and sudden loss of vision in the left eye. Ophthalmoscopic examination revealed a swollen optic nerve and widespread retinal whitening. Follow-up fluorescein angiography showed retinal haemorrhages and occlusion of several arterioles by fat emboli. Vision had not improved two months later.
Park Y-H, Kim KS. Blindness after fat injections. N Engl J Med 2011; 365: 2220.
Treatment for amblyopia: the younger the better
There is a long-held view based on observation and experience that amblyopia treatment is more effective when commenced at a young age rather than in later pre-teen years. This has now been confirmed as a result of a meta-analysis of four randomised amblyopia treatment trials. Children aged between three and five years and those between five and seven years responded similarly to treatment for moderate amblyopia but the younger group having severe amblyopia responded better than the older group. Both younger groups were significantly more responsive than the older seven to 13-year age children.
Holmes JM, Lazar EL, Melia BM, Astle WF, Dagi LR, Donahue SP, Frazier MG et al. Effect of age on response to amblyopia treatment in children. Arch Ophthalmol 2011; 129: 1451–1457.
DIABETES AND OCULAR DISEASE
Diabetic eye disease: some good news
Based on self-reporting, the prevalence of visual impairment in adults having diabetes has reduced from 23.7 per cent in 1997 to 16.7 per cent in 2010. The number of annual visits to optometrists and ophthalmologists did not change significantly during this period.
Centers for Disease Control and Prevention. Self-reported visual impairment among persons with diagnosed diabetes—United States, 1997–2010. Morb Mortal Wkly Rep 2011; 60; 1549–1553.
Screening for diabetic eye disease
A Swedish study followed the course of 1,691 type 2 diabetic subjects over three year intervals. The subjects had diabetes for up to six years, were aged between 48 and 72 years and were free of diabetic retinopathy at recruitment. After three years, 73 per cent had no retinopathy and 28 per cent had developed mild or moderate diabetic retinopathy, but no subject had developed severe non-proliferative or proliferative retinopathy. One subject developed clinically significant macular oedema in one eye. The authors conclude that screening at three-year intervals is adequate for retinopathy in type 2 diabetic people.
Agardh E, Tababat-Khani P. Adopting 3-year screening intervals for sight-threatening retinal vascular lesions in type 2 diabetic subjects without retinopathy. Diabetes Care 2011; 34: 1318–1319.
Arteriolar tortuosity and diabetic retinopathy
Gross retinal blood vessel changes are observed during the progress of the later stages of diabetic retinopathy and include generalised venous dilation and beading, loop formation and venous duplication. A study involving 224 subjects having diabetes, with and without retinopathy, and 103 non-diabetic controls sought an association of retinal vessel tortuosity with early diabetic retinopathy. Those subjects having diabetes were found to be more likely to have tortuous retinal arterioles than the controls, regardless of the presence or absence of retinopathy. This finding suggests that retinal arteriolar tortuosity might be an important clinical sign of early microvascular changes.
Sasongko MB, Wong TY, Nguyen TT, Cheung CY, Shaw JE, Wang JJ. Retinal vascular tortuosity in persons with diabetes and diabetic retinopathy. Diabetologia 2011; 54: 2409–2416.
The social burden of squint starts early
In a Swiss study, photographs of children were digitally altered to provide a virtual identical twin. One image was then altered to simulate various strabismic conditions or remained orthotropic. A group of children aged younger than six years viewed the photographs and were asked to select children to ask to their birthday parties. These children selected guests with no distinction made between orthotropic and strabismic children. Children aged six and older invited strabismic children significantly less often than orthotropic children. The authors argue that corrective surgery should be provided before six years of age where binocular vision is not achievable because negative attitudes toward strabismic children commence in their peers at about that age.
Mojon-Azzi SM, Kunz A, Mojon DS. Strabismus and discrimination in children: are children with strabismus invited to fewer birthday parties? J Ophthalmol 2011; 95: 473–476.
Risk of strabismus: not just refractive error
In the USA approximately two to three per cent of children aged younger than six years have strabismus. A population-based study of the risk of developing of childhood strabismus confirmed the strong association with refractive error, premature birth and maternal smoking. The results also noted a significant familiar component that is independent of refractive error.
Cotter SA, Varma R, Tarczy-Hornoch K, McKean-Cowdin R, Lin J, Wen G, Wei J et al. Risk factors associated with childhood strabismus: the multi-ethnic pediatric eye disease and Baltimore pediatric eye disease study. Ophthalmology 2011; 118: 2251–2261.
Perhaps it's the swing that's the thing
Reduction of intraocular pressure (IOP) remains the only proven effective treatment for open-angle glaucoma; however, reduction of IOP in the majority of cases delays rather than halts optic nerve head damage and the resulting visual loss, even when mean pressures are lowered to or below normal levels. A literature review and comment on this treatment suggests that variations of the IOP, particularly the swings toward higher levels, may be important and a hitherto neglected risk factor for glaucomatous damage. Large variations in blood pressure are known to be an independent risk factor for cardiovascular complications in patients having systemic hypertension and a new treatment strategy has been adopted to smooth out the peaks in these patients. The authors suggest that controlling IOP to eliminate the excessive peak pressures should be considered in management of patients having progressive glaucomatous damage.
Caprioli J, Varma R. Intraocular pressure: modulation as treatment for glaucoma. Am J Ophthalmol 2011; 152: 340–344.
Review of priorities for detection and management of glaucoma
A perspective based on a review of the literature examined the present state of detection and management of glaucoma in resource-poor through to resource-abundant regions. It concluded that the value of glaucoma detection and monitoring procedures varied according to the context of available resources. The authors comment on the proliferation of complex and expensive diagnostic equipment that might be made obsolete before it has been adequately validated. It asks whether we are better off as a result of these technologies, particularly in the context of variability and uncertainty of prognosis both with and without treatment and lack of unequivocal evidence of the value of early treatment. Over the full spectrum of resource availability, tonometry, gonioscopy and optic nerve head assessment were rated as the most important early detection procedures. The omission of visual field assessment and inclusion of gonioscopy in the list might stimulate reassessment of the priorities of the content of undergraduate clinical optometric teaching.
Lieberman MF, Congdon NC, He M. The value of tests in the diagnosis and management of glaucoma. Am J Ophthalmol 2011; 152: 889–899.
ANIMALS AND PUBLIC HEALTH
Arachnophilia: a novel cause of keratitis
A 16-year-old boy had a six-week history of ocular irritation. Slitlamp examination revealed fine hair-like foreign bodies on the corneal epithelium. The problem resolved after removal of the hairs and use of antibiotics and steroids. The boy was advised to avoid a relapse by ceasing to encourage his pet tarantula spider to crawl over his face.
Stagg B. Tarantula hairs as corneal foreign bodies. Case Report Ophthalmol 2011; 2: 323–326.