The prevalence of ocular complications among children with nephrotic syndrome at MNRH was found to be 80%. This was high and probably explained by the high proportion of hypertrichosis among the ocular complications which does not revert in many patients even when medication is stopped (12).
We found no previous studies that stated the prevalence of ocular complications among children with nephrotic syndrome. Majority of the children with NS attending MNRH had one or more ocular complication.
Hypertrichosis was the most frequent ocular complication in this study at 71(71%).This has not been reported by previous researchers among children with nephrotic syndrome. However, it was reported among 23 Dutch asthmatic children on inhaled corticosteroids as an adverse effect. Differences occurred in individual susceptibility; occurrence and reversal of hypertrichosis and could have been the case for the patients we examined(12).
While Epiblepharon (46.6%) was the most prevalent ocular abnormality among Japanese children with NS, it was not reported among our patients. This was probably because Asians have a more anterior insertion of the levator aponeurosis making epiblepharon prevalent even in their general population(13).
Refractive errors were found in 56 children (56%)and a total of 103 eyes; myopic astigmatism being the most frequent 32(29%).This could be explained by the fluctuating intraocular pressures (IOPs) which cause stretching of the globe and transient increases in the axial length resulting in myopic astigmatism(14). In Kampala, the most prevalent refractive error among primary school children was found to be astigmatism at 52% followed by hyperopia which made our findings different from the general population(15). Similarly, other studies also found myopic astigmatism as the commonest refractive error among children with nephrotic syndrome. A study by Gheissari et al(16) found prevalence of myopic astigmatism at 18(24%) (16), Ozaltin recorded myopic astigmatism as the only refractive error among the three children with nephrotic syndrome whom he examined(17) and Agrawal et al in India found myopic astigmatism as the only refractive error at 5(5%) related to steroid therapy among children with nephrotic syndrome(11).
Elevated IOP was recorded in 16(16%) patients. This was comparable to results from similar studies. Gaur found elevated IOP in 10.97% of the children with Nephrotic syndrome he examined in India(18). In Japan, 20% of children with nephrotic syndrome had elevated IOP(7). Agrawal found elevated IOP in 2% of the children with NS that he examined(11). Corticosteroids which are the mainstay of treatment for nephrotic syndrome cause an elevated IOP by increasing resistance of aqueous outflow at the level of the Trabecular meshwork (19).
This current study found PSC in 1(1%) of the children with NS. This was lower than what other studies found elsewhere. In Japan, 33.3% of the children with NS examined by Hayasaka had PSC while Gaur recorded 26.8% in India, Olonan et al reported a similarly high occurrence of 13.6% in Manilla Philippines and Wong recorded 10.3%. The difference in the frequency of PSC among the patients with NS in MNRH from those examined elsewhere could not be explained further since this was the first study in an African population. Cotlier proposed that steroids gain entry into the fiber cells of the crystalline lens, react with specific amino acids causing alterations and protein aggregation leading to lens opacification(20).
In our study, children who were 10 years and above had almost twice risk of developing ocular complications than those between 1 and 5 years. This could be because older children had started treatment earlier and therefore had been exposed to the steroids longer than the younger children as reported by Kobayashi et al., 1974 and Brocklebank et al., 1982(21, 22).
Conclusions and recommendations
We found a high prevalence of ocular complications among children with nephrotic syndrome in this tertiary hospital. The predictor of ocular complications was age greater than 10 years. We recommend that all children with nephrotic syndrome undergo a baseline ocular examination prior to commencement of treatment and be reviewed periodically by an ophthalmologist.
Strengths of the study
It was the first study of this kind in an African population. It is also the only study that has estimated the prevalence of ocular complications among children with nephrotic syndrome.