Scheimpflug imaging in anterior megalophthalmos

Atypical presentations of non-familial anterior megalophthalmos: a rare disease

Anterior megalophthalmos usually presents early in life with megalocornea, deep anterior chamber, raised intraocular pressure, glaucomatous optic nerve damage and iridodonesis/stromal thinning with positive family history. We report atypical features and presentations in two patients (four eyes) with non-familial megalophthalmos. While the first patient, a male, presented at 51 years of age with megalocornea, cataract, phacodonesis, normal pupillary dilatation/normal iris and advanced glaucoma, the second patient presented with iridodonesis with stromal thinning, aphakia and advanced glaucoma. The family history was negative in both patients. The vitreous index was unusually high, >70% in all four eyes, owing to aphakia in the second patient and possible late presentation/variant phenotype in the first patient. Thus, atypical features such as greater vitreous length, absent iris involvement and late-onset adult presentation are common in non-familial anterior megalophthalmos. Clinical surprises due to varied phenotypes should be kept in mind in such cases.

Ocular abnormalities and complications in anterior megalophthalmos: a case series

OBJECTIVES

To describe the clinical and Scheimpflug imaging features in cases of anterior megalophthalmos (AM).

METHODS

Retrospective record review was performed for patients with AM who presented between June 2017 and May 2018. Clinical history, slit lamp examination, Scheimpflug imaging indices (Pentacam-HR, Oculus, GmbH), dilated fundus examination and treatment records were reviewed.

RESULTS

The study included eight eyes of four male patients (mean age 6.5 years, range 4-10 years). Corrected distance visual acuity ranged from finger counting to 20/80. The mean horizontal corneal diameter, central corneal thickness, steep keratometry, flat keratometry, anterior chamber (AC) angle, AC depth, maximum pupil diameter and axial length were 13.8 ± 0.5 mm, 538.7 ± 68.9 µm, 42.8 ± 1.6 D, 41.4 ± 0.9D, 47.0 ± 4.2 degree, 3.8 ± 0.3 mm, 3.9 ± 0.1 mm, and 24.9 ± 0.9 mm, respectively. Posterior dislocation of crystalline lens, vitreous degeneration and rhegmatogenous retinal detachment (consequent of retinal dialysis/atrophic hole/lattice with hole) were noted in seven, eight and five eyes, respectively. Pigment dispersion glaucoma was noted in both eyes of one patient, which was managed with topical anti-glaucoma medication. Vitrectomy with silicone oil tamponade was successful in retinal reattachment in all three eyes that underwent surgery.

CONCLUSION

Scheimpflug imaging helps in demonstrating the corneal and anterior segment pathological changes in AM. The disease extends to involve the zonules, vitreous and retina as well. Ophthalmologists should be able to identify this disorder, recognise and manage the associations and complications.

Trans-scleral explantation of posteriorly dislocated IOL-CTR complex in a case of anterior megalophthalmos with an unusually thin cornea

Anterior megalophthalmos and keratoglobus are characterised by corneal thinning and deep anterior chamber. They are clinically distinguished on the basis of normal to slightly decreased corneal thickness with a large corneal diameter (>13 mm) in case of anterior megalophthalmos, and marked limbus-to-limbus corneal thinning with globular protrusion in keratoglobus. To achieve and maintain a centred and stable intraocular lens (IOL) position in the bag is often difficult in cases of anterior megalophthalmos due to a too large diameter of the capsular bag and ciliary ring. We report a case of a 40-year-old man with features of anterior megalophthalmos with extremely thin cornea. He had spontaneous posterior dislocation of IOL and capsular tension ring (CTR) within the bag after initial successful cataract surgery. The dislocated complex could neither have been repositioned with scleral fixation due to large diameter of ciliary ring nor could it have been explanted through a clear corneal incision due to associated very thin cornea. We performed pars plana vitrectomy and separated the IOL-CTR complex inside the eye and explanted them separately through the sclerotomy, as is done for removal of intraocular foreign body. This avoided incision on the thin cornea. We conclude that this method can be very useful in a similar clinical situation but is complex enough to justify its use in routine cases.

Cataract Surgery in Anterior Megalophthalmos: A Review

Anterior megalophthalmos is characterized by megalocornea associated with a very broad anterior chamber and ciliary ring elongation. It is also called X-linked megalocornea. It is accompanied by early development of cataracts, zonular anomalies, and, rarely, vitreoretinal disorders. Subluxation of a cataract can occur in cataract surgery because of zonular weakness. In addition, in most patients, standard intraocular lens (IOL) decentration is a risk because of the enlarged sulcus and capsular bag. These unique circumstances make cataract surgery challenging. To date, several approaches have been developed. Implantation of a retropupillary iris-claw aphakic intraocular lens may be a good option because it is easier than suturing the IOL and can have better and more stable anatomic and visual outcomes, compared to other techniques.