Significant macular edema in a patient with cone dystrophy and improvement with acetazolamide treatment

Childhood cone-rod dystrophy with macular cyst formation in ABCA4 mutation identified by serial spectral-domain optical coherence tomography

Cone-rod dystrophy (CORD) is a type of progressive hereditary retinal dystrophies that causes cone predominant photoreceptor degeneration characterized by wide genotypic and phenotypic heterogeneity. Macular cyst (MC) occurs very infrequently in the pediatric age group and has rarely been described in CORD. We report a case of young-onset CORD that was affected by an isolated ABCA4 mutation complicated by the development of MC. Through serial spectral-domain ocular coherence tomography MC has been observed to persist for 24 months before its resolution, followed by retinal thinning and macular atrophy with corresponding visual acuity decline. The formation of MC and visual acuity appeared to be directly correlated in ABCA4-related CORD and its manifestation is invaluable in predicting eventual visual loss. We further speculate that dysfunctional outer blood-retinal barrier may play a role in the pathophysiology of MC development in CORD.

Optical coherence tomography in the evaluation of retinitis pigmentosa

BACKGROUND

Optical coherence tomography (OCT) is a non-invasive imaging test that provides easily obtainable and highly reproducible cross-sectional images of the retina. Improved modalities of the OCT that are capable of providing high quality images of not only the retina, but also the deeper structures and vasculature have been developed, including swept-source OCTs and OCT angiography.

MATERIALS AND METHODS

Review.

RESULTS

The use of OCT in the monitoring of retinitis pigmentosa has been well described and numerous signs of disease progression have been studied. Notably among them are the detection of changes to retinal thickness, the ellipsoid zone, the vasculature on OCT angiography, and cystoid macular edema.

CONCLUSION

In this review, we discuss the multiple applications of OCT as a tool in the monitoring of retinitis pigmentosa and its potential use as an outcome measurement in current and future therapeutic endeavors.

CRB1-Related Cystic Maculopathy in Twins Conceived Through Heterologous Fertilization With Variant-Carrying Oocytes

Cystic maculopathy has been associated with genetic disorders such as retinitis pigmentosa, X-linked retinoschisis, cone dystrophy, and foveal retinoschisis. Familial foveal retinoschisis was recently described as a rare disease caused by CRB1 variants. The authors report the phenotype-genotype pattern of a pair of dizygotic twins with early-onset cystic maculopathy due to CRB1 pathogenic variants. The twins were conceived by heterologous fertilization with variant-carrying oocytes. The probands were monitored for a period of 4 years. Next generation sequencing of a panel of genes responsible for retinal dystrophies was performed. Both children carried three pathogenic variants in CRB1: a novel heterozygous truncating variant p.(Val855*) inherited from the father and two known heterozygous missense variants, p.[(Phe144Val; Thr745Met)], inherited from the oocyte donor. The findings confirm that CRB1 variants can be responsible for foveal retinoschisis with variable clinical expressivity ranging from schitic macular alteration to early-onset forms of cystic maculopathy. The authors highlight the importance of exome analysis of gamete donors to assess the likelihood of recessively inherited disorders by means of a prediction algorithm able to combine parent and donor exome data. [J Pediatr Ophthalmol Strabismus. 2020;57:e19-e24.].

Topical carbonic anhydrase inhibitors in macular edema associated with Alström syndrome

BACKGROUND

Alström syndrome is a rare genetic ciliopathy caused by a mutation in the ALMS1 gene. The syndrome is characterized by cone-rod dystrophy, dilated myocardiopathy, childhood obesity and sensorineural hearing loss. To date, cystoid macular edema has not been reported.

METHODS

A female affected by Alström syndrome developed bilateral cystoid macular edema evidenced by optical coherence tomography. A topical carbonic anhydrase inhibitor was prescribed.

RESULTS

Complete resolution of the cystoid macular edema was achieved, though visual acuity did not improve.

CONCLUSIONS

Topical carbonic anhydrase inhibitors may have a role in the treatment of macular edema in syndromic retinal dystrophies such as Alström syndrome.

Retinitis pigmentosa and bilateral cystoid macular oedema in a patient heterozygous for the RIM1 mutation previously associated with cone-rod dystrophy 7

BACKGROUND

Autosomal dominant cone-rod dystrophy 7 (CORD7) has been previously associated with the RIM1 c.2459G>A (Arg820His) mutation. Cystoid macular oedema (CMO) is a rare feature of CORD and has not been described in CORD7. We report a patient who was heterozygous for the RIM1 mutation with bilateral CMO and who manifested a retinitis pigmentosa phenotype.

MATERIALS AND METHODS

The patient's medical notes were retrospectively reviewed over an 18-month period. Genetic testing was performed by next generation sequencing for a panel of 176 genes associated with retinal dystrophy.

RESULTS

A 34-year-old man presented with a 5-year history of bilateral floaters and blurred vision. Visual acuity was 20/23 and 20/33 in the right and left eyes, respectively. Optical coherence tomography scans revealed bilateral CMO. Goldmann visual field tests detected mid-peripheral ring scotomas. Electrodiagnostic testing was overall consistent with a primary photoreceptor abnormality involving both rods and cones. Subsequent genetic testing identified heterozygosity for the RIM1 c.2459G>A (Arg820His) mutation. Various treatments for CMO were trialled unsuccessfully. However, at his latest clinic appointment the CMO had partially improved following topical brinzolamide therapy. Most recent visual acuity was 20/25 in the right eye and 20/24 in the left eye.

CONCLUSIONS

This is the first reported case of bilateral CMO in association with the RIM1 mutation. Overall, our findings were more consistent with a phenotype of retinitis pigmentosa. This could imply that the RIM1 mutation causes diverse retinal dystrophies, or that the previously described CORD7 phenotype resulted from a different variant on the same haplotype.