Electrophysiological investigations in retinal metabolic disease: Their range and application

Vitamin A deficiency retinopathy related to medical interventions in a Swiss cohort: a case series

AIMS OF THE STUDY

Vitamin A deficiency retinopathy is a potentially blinding disease. In developed countries, vitamin A deficiency due to malnutrition is rare. However, vitamin A deficiency can be caused by malabsorption resulting from bowel resection or medication. In this retrospective study, we present five cases of vitamin A deficiency retinopathy related to malabsorption secondary to medical interventions.

METHODS

Electronic charts over a ten-year period (2012-2022) were screened for vitamin A deficiency retinopathy. Only patients with vitamin A deficiency confirmed by laboratory tests were included. Symptoms, medical history, visual acuity, optical coherence tomography, fundus autofluorescence, electrophysiological examination, and vitamin A levels were reviewed.

RESULTS

Five eligible cases were identified. Median age was 44.7 years (range 22.2-88.9), median duration of ocular symptoms prior to diagnosis was 14 months, and median visual acuity was 1.0 (range 0.5-1.0, Snellen, decimal). Three patients had a history of bariatric surgery, one patient had a small bowel resection and was on octreotide treatment, and one patient suffered from cystic fibrosis and had a history of small bowel resection and severe hepatopathy. Optical coherence tomography showed various abnormalities, including a reduced interdigitation zone, subretinal drusenoid deposits, and a thinned outer nuclear layer. Electroretinogram findings ranged from abnormal oscillatory potentials to non-recordable rod responses.

CONCLUSIONS

Vitamin A deficiency retinopathy can occur following medical interventions associated with malabsorption. In cases of night blindness, vitamin A levels should be measured.

Treatment of vitamin A deficiency retinopathy with sublingual vitamin A palmitate

PURPOSE

To report treatment of vitamin A deficiency retinopathy with sublingual vitamin A drops.

METHODS

Case report with review of the literature.

RESULTS

A 69-year-old Caucasian woman with a history of small bowel resection presented with progressive symptoms of bilateral nyctalopia and decreased visual acuity. Ophthalmic examination revealed bilateral conjunctival xerosis and fine white granular deposits in the midperipheral retina suggestive of vitamin A deficiency. Full-field electroretinogram (ERG), multifocal ERG (mfERG), and two-color dark adaptometry revealed significant impairment of rod and cone photoreceptor function. Kinetic perimetry demonstrated depressed macular sensitivity with constriction of the finer isopters. After 5 months of treatment with sublingual vitamin A drops, the patient's vision, ERG, mfERG, dark adaptometry, and perimetry normalized. A review of the literature summarizing the electrophysiologic testing in vitamin A deficiency is also discussed.

CONCLUSIONS

This case highlights novel observations on the effects of sublingual vitamin A supplementation for acquired vitamin A deficiency retinopathy. Sublingual vitamin A may represent a viable and efficacious treatment modality for vitamin A deficiency.

Clinical investigation of retinitis pigmentosa

The diagnostic features and future research directions of retinitis pigmentosa were documented in this update and review of the subject. An extensive and current bibliography is provided.

Attempts to define the minimal serum level of vitamin A required for normal visual function in a patient with severe fat malabsorption

A case with severe malabsorption of fat soluble vitamins is described. The malabsorption developed after an intestinal bypass operation due to morbid obesity. Night blindness occurred as the first symptom of vitamin A deficiency. The cone visual sensory threshold was elevated about one log unit and the rod threshold abot two and a half log units. No changes of the a- and b-waves of the electroretinogram (ERG) was observed. However, during the initial phase of very low serum reninol level (0.21 mumol/l) the summed amplitudes of the oscillatory potentials (OPs) were lower. After parenteral therapy with vitamin A the night blindness disappeared and the dark-adapted rod and cone threshold sensitivity recovered to normal. However, the time-course of rod adaptation first reached normal levels after 5 months. The amplitudes of the OPs of the ERG response returned to normal when the serum retinol level had increased close to normal. Serum retinol levels of 0.7 mumol/l or higher were always associated with normal or close to normal dark-adapted rod sensitivity. However, a normal serum retinol level (> 0.95 mumol/l) and a normal dark-adapted rod threshold sensitivity were not always associated with a normal time-course of the rod adaptation. It is concluded, that the maintenance dosage of vitamin A must be individualized and that patients who have undergone jejuno-ilea bypass surgery must be carefully monitored for vitamin A deficiency by both serum levels and dark adaptation measurements.

Keratomalacia on a 'healthy diet'

The case is described of a 39-year-old man with previously undiagnosed chronic schizophrenia and with bilateral keratomalacia secondary to his bizarre diet. He presented with a perforation of the right cornea which required an emergency penetrating keratoplasty. The difficulties of clinical management of a patient with an overt psychosis and the use of serum retinol levels to monitor treatment are described. Causes of vitamin A deficiency seen in Great Britain are discussed.

Retinitis pigmentosa

The authors review the symptomatic and genetic aspects of the various entities of isolated retinitis pigmentosa (R.P), both in its typical form and in the forms associated with the affection of other ocular tissues. Syndromes in which R. P. is associated with the affection of other organs and systemic disorders are also cconsidered. Origin, diagnosis and the course of the disease are discussed with regard to electrophysiology, histopathology, fluorescein angiography and biochemistry. Animal research has provided new realizations about the ultrastructure and physiological mechanisms of retinal photoreceptors, and better understanding of abnormal changes. The possible pathogenesis of the human disease, based on research findings, is onsidered. Although R.P. is generally thought to be to be an "untreatable" disease, therapy may be effective in several pathological entities. Methods and results of therapy with vitamins, light deprivation and vision aids are discussed.