I chose this article in view of 2 patients whose clinical cases I have summarised.  

Whole exome sequencing of known eye genes reveals genetic causes for high myopia. Haarman et al. Human Molecular Genetics, 2022, Vol.31, 19, 3290-3298.

 “Eye genes known to cause retinal dystrophy, developmental or syndromic disorders can cause high myopia without apparent clinical features of other pathology.”

The aim of this study was to determine the benefit(s) of whole exome sequencing (WES) using an eye disorder gene panel of European patients with high myopia ( <-6 D). 113 patients with high myopia were studied, 53% were children < 12 yrs old, 13.3% were aged 12-18 yrs and 34% were > 18 yr. 82 (73%) presented with isolated high myopia, 17 (15%) presented with systemic involvement and 14 (12%) presented with other ocular features. Pathogenic variants were located in genes involved in retinal dystrophies, connective tissue disease, non-syndromic high myopia and disorders of ocular development. A genetic cause was identified in 1 out of 5 patients and 1 out of 7 patients with isolated high myopia.

Relevance to clinical practice: visual development or decline, myopic progression and response to treatment is dependent on the genetic defect underlying the disease; and with a risk of related systemic features there is a need to consider referring to another medical specialist.

Case Summary 1

April’22:  2 yrs 2mths, male, Plunket referral due to maternal concern child holds toys close to face. Ethnicity: NZ European   BH: FT, c/s    GH: good, nil meds, NKDA FH: Mum -6.50DS, Mat Aunt -3.50DS, Mat Gran -14DS.

CT: NAD. disc/retina normal, Gls prescribed R -11.0  L -10.0

May’23: 3 yrs 3mths VA aided R 0.2  L 0.3  crowded Kay pictures

July’23: Gls updated R -12.0/ -1.0 x 10   L -12.0/ -1.0 x 170

Oct’23: VA aided R 0.250  L 0.275 crowded Kay pictures. Prescribed 0.05% atropine eye drops (advised by Dr Justin Mora). Referred to Dr Sarah Hull.

Jan’24: 3 yrs 11mths VA aided R 0.325  L 0.350  crowded Kay pictures. Ishihara OU 17/17 plates correctly identified. Axial Length IOLMaster  R 25.40 mm  L 25.43 mm (av. 21-22 mm for ages 3-4yrs)

Case Summary 2

Sept’23: 16 mths, male, GP referral ? LX(T) observed from 1mth old. Ethnicity: Maori/NZ European     BH: FT, forceps delivery   GH: good, nil meds   FH: nil of note

CT: ? int dist R X(T)  Spotscreener R < -7.50   L +0.25  (no squint), no buphthalmos, no cataract but difficult dilated exam in clinic and listed for EUA.

Jan’24 EUA: IOP 11/11 iCare, corneal diameter 12 mm R & L, RE myopic fundus, R larger myopic disc 0.7/0.3, Gls prescribed R -7.0  L plano. Referred to local optometrist for CL trial.

Reflective Practice

Grace’s journal club article (December 2023) “Homocystinuria and ocular complications- A review” and her clinical case study underlines the importance of a genetic diagnosis for a child with progressive myopia in the absence of axial length increase.

Libby Kelly.