Achondroplasia and Macular Coloboma.

Achondroplasia is an autosomal dominant congenital disorder of enchondral ossification. It is clinically characterized by low stature, craniofacial deformity, and vertebral malformation. Associated ophthalmic features include telecanthus, exotropia, angle anomalies, and cone-rod dystrophy. A 24-year-old male presented with decreased vision bilaterally and typical achondroplasia. The best corrected visual acuity was 20/70 in both eyes. Anterior segment examination was normal. Fundus examination revealed a well-demarcated circular paramacular lesion in both eyes. As macular coloboma and achondroplasia are developmental disorders, the funduscopic examination is required in patients with achondroplasia.

INTRODUCTION

Achondroplasia is a congenital disorder of bone formation characterized by short stature, craniofacial malformations, and vertebral anomalies. Ophthalmic features including telecanthus, strabismus, and anterior chamber anomalies are frequently found.1 Duane's retraction syndrome and cone-rod dystrophy have been reported in association with achondroplasia.2 Macular coloboma is an atypical coloboma that is thought to result from incomplete differentiation of the arcuate bundle along the horizontal raphe during development. We report a patient with achondroplasia and paramacular cloboma.

CASE REPORT

A 24-year-old Azeri male presented with a chief complaint of blurred vision in both eyes. He was diagnosed with achondroplasia in early childhood. He was born at term with normal birth weight. There was no history of hereditary ocular or systemic disease. This patient had characteristic features of achondroplasia (i.e., short stature, lumbar lordosis, short proximal long bones, large hands, frontal bossing, and flat nasal bridge) [Figure 1]. His height was 108 cm. Best corrected visual acuity was 20/70 in the right eye with −0.75 + 1.25 × 60° and 20/70 in the left eye with OS: +0.25 + 0.50 × 130°.

Figure 1

Clinical appearance of a 24-year-old male presenting with typical achondroplasia

Pupils were equal in size, round and reactive to light with no reverse afferent pupillary defect. Ocular motility was normal in both eyes and slit lamp examination was unremarkable. The intraocular pressure was 12 mm Hg by Goldmann applanation tonometry.

Central corneal thickness values of the right and left eyes were, 561 and 557 μ, respectively. Dilated fundus examination revealed a well-demarcated circular macular lesion in both eyes. In the right eye, this lesion was approximately 2.5 disc diameters (DD) in width and 2.7 DD in length. In the left eye, this lesion was approximately 2.5 DD in width and 2.8 DD in length. The border of the lesions was pigmented. Underlying choroidal and overlying retinal vasculature appeared normal. In addition, a stalk of tissue emanated from the optic disc and coursed into the vitreous [Figure 2].

Figure 2

Fundus photograph showingmacular coloboma in left (a) and right (b) eyes

Fluorescein angiography of the posterior segment and optical coherence tomography of the optic nerve head (Stratus; Carl Zeiss GmbH, Jena, Germany) were performed [Figures 3 and 4].

Figure 3

Fluorescein angiography of both eyes showing macular coloboma without any other retinal lesion

Figure 4

Optical coherence tomography showing attenuated retinal nerve fiber layer of both eyes especially the left eye

Due to the background maculopathy, the patient could not appropriately fixate on the target during image acquisition resulting in slightly decentered fluorescein angiography images [Figure 3].

DISCUSSION

Achondroplasia is the most common hereditary disorder that causes dwarfism, and its prevalence is 1/15,000–1/40,000. It has an autosomal dominant trait that occurs as a result of the mutation in genes encoding fibroblast growth factor receptor 3.3 Chorioretinal coloboma develops due to an incomplete closure of the optic fissure, during 6–7 weeks in the embryonic period. Concurrent malformation of other organs has also been documented with achondroplasia.4

Maumenee and Mitchell5 proposed the hypothesis that this disease entity occurs due to genetic defects of a single gene. They5 noted that, it occurs in the early embryonic stage and features a high incidence of systemic and central organ malformation.

As macular chorioretinal coloboma is seldom reported in the literature, no epidemiologic or demographic data are currently available. Currently, only isolated case reports, and no case series have been published. Therefore, statistical data such as incidence and prevalence, gender predilection, age, race, or other demographic characteristics would be purely speculation.

Previous reports have linked macular coloboma with other possible ocular conditions including blepharophimosis, abnormal horizontal narrowing of the palpebral aperture, and anomalous retinal vasculature including situs in versus.6

Yoo et al.7 reported a case of chorioretinal coloboma in a patient with achondroplasia. To our knowledge is the only case report in the literature.

CONCLUSION

In this case report, we presented the correlation between bilateral macular coloboma and achondroplasia. As chorioretinal coloboma and achondroplasia are developmental disorders in the embryonic stage, we recommend that the patients with achondroplasia should be closely monitored for ocular abnormalities associated with the disease which can affect learning of preschool and school-age children.

Financial support and sponsorship

Nil.

Conflicts of interest

The authors have obtained appropriate patient consent for the information published in this article.