This is perhaps the largest series of non-traumatic Ectopia Lentis reported thus far in African children. The mean age at presentation was 8.9 years and the age range was similar to the range of 5-12 years reported by Shafique et al16 in Pakistan. The youngest child in our cohort was 2 years of age and this buttresses the findings of a study in China which showed that greater than 50% of patients with Marfan Syndrome acquired Ectopia lentis before 5 years of age or during early childhood.10 However, the majority of patients in our series presented at an age when amblyopia is likely to have developed. The mean age at surgery was 9.2 (±3.76) years and this was higher than 70.3months (5.86years) reported by Hsu et al.13 Some other studies have reported younger median age of 52 months (4.33years) and 4.8years.12,14
The best corrected visual acuity (BCVA) at presentation was poor in all our patients. This is similar to reports by Hsu et al13 in USA, Wu-Chen et al 17 in USA and Noorani et al18 in Pakistan. This we believe is due to the combination of uncorrected high refractive errors and amblyopia due to the late presentation we observed in our patient population.
More than half of the eyes in our series had superior displacement of the lens. This is contrary to findings by Shafique et al16 who reported 75% inferior subluxation. This could be explained by the fact that more patients in our series had features suggestive of Marfan syndrome in contrast to homocystinuria reported in their study.
A significant proportion of our patients had high refractive errors at presentation. This is similar to the high myopic astigmatism reported by Hsu et al.13 Also, lens opacities were seen in 12 (24%) eyes of our patients; which is quite similar to the 20% reported by both Shafique et al16 and Noorani et al.18 A combination of these, in addition to the older age at presentation and the extent of lens subluxation with respect to the visual axis would increase the risk of amblyopia in these patients.
The pedigree charting of 5 patients in our cohort who belong to 2 generations of the same family underscores the need for a detailed family history and examination of all family members. The proband, aged 13 years, had been enrolled in the school for the blind due to poor vision and was referred to our clinic from the school. Following satisfactory visual improvement with surgery and aphakic spectacles, her sister, brother, mother, nephew and niece also presented to the eye clinic for treatment. All these relatives except her mother are among the patients in this case series. Similarly, Noorani reported that a third of their patients had familial ectopia lentis.18
Management of patients with Ectopia Lentis should be comprehensive with respect to diagnosis, detection of systemic comorbidities, counselling and examination of at-risk relatives, indication and timing of surgery, surgical approach, visual rehabilitation and need for long-term follow up. In view of the progressive nature of the disease and the variability among patients, it is challenging to establish an absolute standard of care. There are still controversies as to the adequacy of conservative management.11 A lack of improvement in vision with conservative approach is the commonest indication for surgery.15
For the patients who had surgical management in our series, lensectomy with anterior vitrectomy was performed in 95% of the eyes and the limbal route was used in majority of the eyes. This was largely due to surgeons’ preference and lack of facilities for posterior vitrectomy in our center which is the scenario in most resource poor settings. These eyes were all left aphakic. Some previously reported postoperative complications of aphakia include transient ocular hypertension, transient vitreous hemorrhage, wound dehiscence and glaucoma secondary to pupillary block.17
Postoperatively, the best corrected visual acuity was ≥6/18 in only about half of the eyes in our series. This outcome could be attributed to amblyopia as they had high ametropia and late presentation. Even in the absence of any of these, ectopia lentis in a child is a known risk factor for amblyopia.2,17 Furthermore, the sub-optimal optical correction of surgical aphakia with aphakic spectacles could be contributory.
Noorani et al18 in their large cohort of 54 surgical eyes also corrected surgical aphakia using aphakic spectacles and contact lenses but noted significant visual improvement with 71% achieving ≥6/18. They attributed the poor postoperative vision of 6/60 - HM to preoperative glaucoma present in half of their patients and irreversible amblyopia in a about third18 Other identifiable factors responsible for the poorer BCVA include older age at surgery, short follow up duration, mild visual axis opacification, and residual refractive errors.12
On the other hand, better visual outcomes have been recorded in some studies.9,17,19 Even though 78% of their patients were >5years at the time of surgery and there was no IOL implantation, Halpert and BenEzra9 were able to achieve VA ≥ 20/40 (6/12) in 80% (47) of eyes. Wu-Chen et al17 also recorded VA improvement in all cases and BCVA was ≥20/30 (6/9) in 82.4% despite a mean age of 7.7 years and no IOL insertion. Their longer mean follow-up duration of 4.6years and 8.5years respectively could have been a factor in this. Even with shorter duration of follow up of 1 year Nb et al19 documented BCVA of ≥20/30 in 84% postoperatively. This may be attributed to use of intraocular lenses in their cohort which allows for better visual rehabilitation.
Postoperative retinal detachment observed in this series is not uncommon and has been reported in other studies.9,18 Retinal detachment was reported up to 2 years post lensectomy in a previous series with improved visual acuity post repair.9 Postoperative elevated IOP was also noted in two eyes in our study. Even with a mean follow-up of 4.6years Halpert and BenEzra9 recorded normal IOP in the range of 12-18mmHg throughout the follow up period in all their patients. Long-term follow-up to monitor for glaucoma is required for children with ectopia lentis.
There are some limitations to our study. The diagnosis of Marfan syndrome in our series was difficult because of the absence of genetic diagnostic facilities to detect gene mutations. Notwithstanding, Ectopia lentis is an ocular manifestation that is considered a major diagnostic criterion and other suggestive clinical features were present leading to a clinical diagnosis of Marfan syndrome in about half of our patients. The retrospective nature of the study made retrieval of data a challenge with some missing data. Furthermore, some patients were lost to follow-up.