Congenital cataract is one of the most common treatable causes of visual impairment and blindness during infancy, with an estimated prevalence of 5 to 15 per 10,000 children in developing countries.1 Cataract produces prolonged visual deprivation that causes an irreversible loss of vision. Although a decent amount of literature is available pertaining to bilateral cataracts, the same cannot be said of unilateral cataracts.
The rate of unilaterality in congenital cataract has been reported to be from 19.6% to 55.5% by various studies.2–4 In most cases, there is no history of childhood cataract in the family, the child has no associated systemic illness, and no cause for the cataract can be identified. Sometimes, there are other structural issues in the eye besides the cataract, such as the affected eye being smaller than the fellow eye, suggesting that complications occurred during the development of the eye before birth. Unilateral cataract is usually an isolated, sporadic incident. However, it can be associated with ocular abnormalities such as posterior lenticonus, persistent fetal vasculature, or posterior pole tumors.
Although various associations of unilateral cataract are known, its relative frequency has not been explored in detail. Moreover, studies have shown that parameters such as axial length or corneal curvature are linked to the development of cataract in one eye, with the other eye developing normally.5,6 Our study aimed to analyze demographic and clinical characteristics of children with unilateral cataract.
Patients and Methods
An observational, cross-sectional study was conducted at the Dr. Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. Patients 15 years of age or younger who presented with unilateral cataract to the lens clinic of our center between 2013 and 2015 were recruited. Patients in whom an acquired cause of cataract (eg, trauma, uveitis, drug use, or radiation) could be identified were excluded from the study. Only patients with primary congenital or infantile cataract were included in the study. Written informed consent was obtained from the parents and approval to conduct the study was granted by the institution's ethics committee.
A detailed anterior and posterior segment evaluation was performed. In cases in which cataract precluded posterior segment examination, patients underwent B-scan ultrasonography. Cataract morphology was studied preoperatively on slit-lamp examination or using intraoperative ultrasound biomicroscopy, depending on the patient's age and cooperation. Persistent fetal vasculature was classified as anterior if the cataract was associated with elongated ciliary processes or vascularized posterior capsular plaque; posterior if the stalk arising from the disc, associated retinal detachment, or a Bergmeister papilla were noted; or combined if features of both anterior and posterior classifications were noted. Age at detection and presentation, presenting complaints, distance from the treatment center, morphology of cataract, axial length, keratometry, and corneal diameter were recorded for each case. Age at detection was defined as the age at which the parents, pediatrician, or local ophthalmologist first noted an abnormality in the child's eye and was obtained by taking a detailed history from the parents. Age at presentation was defined as the age at which the patient first presented to our center. Descriptive statistics for normally distributed variables were reported as mean ± standard deviation.
Results were analyzed using the Fisher's exact and unpaired t tests. A P value of less than .05 was considered significant, with a confidence interval of 95%. Statistical analysis was performed using the Statistical Package for the Social Sciences software (version 17.0; IBM Corporation, Armonk, NY).
A total of 76 patients with unilateral cataract who met the inclusion criteria were recruited in the study. History, examination findings, and investigation results of all patients were collected and compiled during a period of 2 years from 2013 to 2015.
Patients often presented with more than one complaint. Most (n = 60) parents of the patients complained of a white opacity (leukocoria), followed by deviation, small size of the eye, and the child squeezing the affected eye in bright light. In 11 cases, parents were able to identify defective vision after noticing leukocoria and deviation (Table 1).
The etiology of unilateral cataract showed that 45 (59.21%) cases were idiopathic. Persistent fetal vasculature accounted for 21 (27.63%) cases. A preexisting posterior capsular defect and posterior lenticonus were also noted to be the causes of cataract in a few cases (Table 2).
Etiology of Cataract
Because persistent fetal vasculature was the most common identifiable cause of unilateral cataract in our study, further statistical analysis was performed on two groups: no persistent fetal vasculature (control) and persistent fetal vasculature.
In the control group, the mean age at detection was 27.58 ± 37.02 months (median: 8 months) and the mean age at presentation was 55.613 ± 45.21 months (median: 48 months). A predilection toward the male sex was noted in our study. There were 34 males and 21 females, with a male:female ratio of 1.6:1. The laterality analysis showed that the right eye was affected in 52.72% and the left eye was affected in 47.27% of cases.
Total cataract was the most common type, followed by mixed, posterior capsular plaque, zonular, nuclear, membranous/partially absorbed, and anterior capsular (Figures 1–2). When multiple morphological types of cataract coexisted, they were considered to be mixed cataract (Table 3).
Cataract morphology. (A) Total cataract. (B) Total cataract with wrinkled anterior capsule with bleeding vessels and prominent ciliary processes. (C) Posterior capsular plaque with thin persistent fetal vasculature stalk. (D) Posterior capsular plaque with subcapsular cataract. (E) Posterior lenticonus with posterior capsular cataract. (F) Unilateral lamellar cataract.
Ultrasound biomicroscopy showing (A) lamellar cataract, (B) anterior and posterior capsular cataract, (C) total cataract, and (D) anterior capsular cataract.
The mean corneal diameters (white-to-white) were 11.36 ± 0.73 and 11.11 ± 1.08 mm in the normal and affected eyes, respectively. No statistically significant difference was noted between the two groups (P = .1579).
The difference in axial length was not statistically significant between the eyes (mean axial length of normal and affected eyes: 21.87 ± 1.50 and 21.27 ± 1.89 mm, respectively; P = .0743).
On analyzing the difference in keratometry, corneas of the affected eye were found to be steeper (44.55 ± 2.37 diopters [D]) compared to the fellow eye (43.72 ± 1.82 D). This difference was statistically significant (P = .0464).
Persistent Fetal Vasculature Group
Eyes with persistent fetal vasculature were studied as a separate group because it was the most common identifiable cause of unilateral cataract in our study. The mean age at detection was 6.17 ± 8.42 months (median: 5 months) and the mean age at presentation was 14.83 ± 17.75 months (median: 10 months). A predilection toward the male sex was noted. The left eye was involved in 61.9% of cases.
The most common cataract morphology in the persistent fetal vasculature group was noted to be posterior capsular plaque, followed by a marginally lower incidence of total cataract (Table 3). Elongated ciliary processes were noted in 11 of the 21 cases of persistent fetal vasculature (Figure 2). Eleven cases had isolated anterior persistent fetal vasculature and the remaining cases had features of both anterior and posterior persistent fetal vasculature. Isolated posterior persistent fetal vasculature was not a part of our inclusion criteria.
Statistically significant differences in axial length, keratometry, and corneal diameters were observed in eyes with persistent fetal vasculature when compared to the fellow eye. The mean axial lengths of the affected and normal eyes were 19.32 ± 1.54 and 20.35 ± 1.59 mm, respectively (P = .027). The mean keratometric values were 44.38 ± 2.26 and 46.48 ± 3.16 D in the normal and affected eyes, respectively (P = .0176). The mean corneal diameters were 11.38 ± 0.74 and 10.71 ± 0.89 mm in the normal and affected eyes, respectively (P = .0114).
The distance traveled by all patients to reach the treatment center was studied. Patients came from a distance ranging between 5 and 1,100 km, with a median distance of 211 km. A plot of delay in the presentation (the time between detection and presentation) versus the distance from the treatment center revealed a positive correlation (Spearman's correlation coefficient = 0.919) (Figure 3).
Time interval between detection and presentation (in months, x axis) vs distance from the treatment center (in kilometers, y axis).
Unilateral cataract is an intriguing entity. The fellow eye is within normal limits considering the biometric parameters. The literature shows insufficient data about the demography and clinical characteristics of patients with unilateral cataract.
Unilateral cataract is usually an isolated, sporadic incident. Similar to Hartmann et al.'s7 and Lim et al.'s8 studies, the cause for cataract could not be determined in more than 50% of the cases in our study.
Male predominance has been a constant finding in almost all studies of pediatric cataract. A previous study completed at our center on the lenticular abnormalities in children resulted in males constituting 66% of the patients.9
A study performed in the United Kingdom by Rahi and Dezateux3 resulted in a median age of detection at 8 weeks. The delay in detection and subsequent presentation in our study can be attributed to the lack of awareness and poor literacy levels, as shown in a study by Mwende et al.2
In a retrospective analysis of 59 patients with congenital cataract conducted by Fakhoury et al.,10 it was observed that leukocoria and strabismus led to a diagnosis in 24% and 19% of cases, respectively. Forty-one percent of their cases were detected by routine screening. In a developing country such as ours that deals with a lack of awareness and routine screening practices, most cases are detected when leukocoria and strabismus become evident and the critical period11 of surgery has passed. In a previous study,9 it was observed that the most common complaint in cases of congenital and developmental cataract was leukocoria, followed by deviation (30%) and nystagmus or nystagmoid movements (15%).
The most common cataract morphology in the control group was total cataract. Posterior capsular plaque was the most common presentation in the persistent fetal vasculature group, followed by total cataract. In Hartmann et al.'s study,7 posterior capsule plaque was observed in 88% of the cases and nuclear cataract was present in 54%. This difference in presentation may be attributed to the late age of presentation in our country, at which point the cataract has progressed to a stage of total cataract.
In our study, a relatively higher number of cases (10.5%) were reported to have preexisting posterior capsular defect. Vasavada et al.12 found the prevalence of preexisting posterior capsular defect in congenital cataract to be approximately 6.75%. The presence of characteristically chalky white spots on the capsule was noted to be an indicator of a preexisting posterior capsular defect.
No significant difference in axial length was noted in the affected eye when compared to the fellow eye in the control group in our study. Trivedi and Wilson5 reported shorter axial lengths in unilateral cases of cataract. Capozzi et al.6 studied 39 patients with unilateral cataract and concluded that no statistically significant differences existed between axial lengths in the eyes with and without cataract.
An analysis of our data suggested that eyes with unilateral cataract have steeper corneas compared to the normal eye. This is in agreement with the study by Trivedi and Wilson,5 in which they reported that eyes with cataract occurring unilaterally have steeper keratometric values compared to the normal eye. The study by Capozzi et al.6 also concurs with our findings, wherein they also observed steeper corneas in eyes with versus without cataract.
Persistent fetal vasculature had an incidence of 27.63% in our study, whereas Hartmann et al.'s7 study reported an incidence of 22%. In our study, the median ages at detection and presentation were earlier in eyes with persistent fetal vasculature than in eyes with idiopathic unilateral cataract. This difference was possibly due to the smaller size of the affected eye, which was noticed early by the parents compared to the leukocoria alone. Hunt et al.13 found that the mean age at presentation for eyes with persistent fetal vasculature was 44 days. In our study, the left eye seemed to be involved more than the right eye in the persistent fetal vasculature group. Similar observations were noted by Hunt et al.,13 who reported an incidence of 55% in the left eye, and by Sun et al.,14 who reported an incidence of 84.6% in the left eye.
When comparing the corneal diameters of the normal and affected eyes, we noted that eyes with persistent fetal vasculature had smaller corneal diameters. Because microphthalmia is a key feature of persistent fetal vasculature, an axial length less than the fellow eye was noted in the affected eye.15,16 Keratometry analysis of eyes with persistent fetal vasculature revealed that corneas in the affected eyes were steeper when compared to the fellow eyes. Asbell et al.17 concluded that eyes with persistent fetal vasculature had steeper corneas than their fellow normal eyes at any given age.
A child presenting with a small eye with unilateral cataract, particularly a posterior capsular plaque, should alert the surgeon to actively look for persistent fetal vasculature. Careful ultrasound-guided B-scan ultrasonography should be performed because a thin stalk of persistent fetal vasculature can be missed. However, the presence of elongated ciliary processes along with the above features is almost always diagnostic.15,16
We noted a positive correlation between the delay in presentation and distance from the treatment center. This implies that parents are forced or tend to delay the treatment if their place of residence is far from the center of treatment. The duration of travel and lack of good conveyance facilities can be held responsible for this tendency.2 Poor socioeconomic status and delayed referral to the higher center are other important causes for delayed presentation.
A significant delay between diagnosis and intervention could be abridged by providing better health care facilities for early diagnosis and management in rural areas. The need for early referral to a higher center if adequate facilities are not available should be emphasized. It is imperative to increase awareness among the parents, pediatricians, and ophthalmologists about the disease and its potential to cause an irreversible loss of vision.
- Foster A, Gilbert C, Rahi J. Epidemiology of cataract in childhood: a global perspective. J Cataract Refract Surg. 1997;23:601–604. doi:10.1016/S0886-3350(97)80040-5 [CrossRef]
- Mwende J, Bronsard A, Mosha M, Bowman R, Geneau R, Courtright P. Delay in presentation to hospital for surgery for congenital and developmental cataract in Tanzania. Br J Ophthalmol. 2005;89:1478–1482. doi:10.1136/bjo.2005.074146 [CrossRef]
- Rahi JS, Dezateux C. Congenital and infantile cataract in the United Kingdom: underlying or associated factors: British Congenital Cataract Interest Group. Invest Ophthalmol Vis Sci. 2000;41:2108–2114.
- Rana AM, Raza A, Akhter W. Congenital cataracts: its laterality and association with consanguinity. Pakistan Journal of Ophthalmology. 2014;30:187–192.
- Trivedi RH, Wilson ME. Keratometry in pediatric eyes with cataract. Arch Ophthalmol. 2008;126:38–42. doi:10.1001/archophthalmol.2007.22 [CrossRef]
- Capozzi P, Morini C, Piga S, Cuttini M, Vadalà P. Corneal curvature and axial length values in children with congenital infantile cataract in the first 42 months of life. Invest Ophthalmol Vis Sci. 2008;49:4774–4778. doi:10.1167/iovs.07-1564 [CrossRef]
- Hartmann EE, Lynn MJ, Lambert SRInfant Aphakia Treatment Study Group. Baseline characteristics of the Infant Aphakia Treatment Study population: predicting recognition acuity at 4.5 years of age. Invest Ophthalmol Vis Sci. 2014;56:388–395. doi:10.1167/iovs.14-15464 [CrossRef]
- Lim Z, Rubab S, Chan YH, Levin AV. Pediatric cataract: the Toronto experience-etiology. Am J Ophthalmol. 2010;149:887–892. doi:10.1016/j.ajo.2010.01.012 [CrossRef]
- Khokhar S, Agarwal T, Kumar G, Kushmesh R, Tejwani LK. Lenticular abnormalities in children. J Pediatr Ophthalmol Strabismus. 2012;49:32–37. doi:10.3928/01913913-20110614-01 [CrossRef]
- Fakhoury O, Aziz A, Matonti F, Benso C, Belahda K, Denis D. Epidemiologic and etiological characteristics of congenital cataract: study of 59 cases over 10 years. J Fr Ophtalmol. 2015;38:295–300. doi:10.1016/j.jfo.2014.10.012 [CrossRef]
- Birch EE, Stager DR. The critical period for surgical treatment of dense congenital unilateral cataract. Invest Ophthalmol Vis Sci. 1996;37:1532–1538.
- Vasavada AR, Praveen MR, Nath V, Dave K. Diagnosis and management of congenital cataract with preexisting posterior capsule defect. J Cataract Refract Surg. 2004;30:403–408. doi:10.1016/S0886-3350(03)00502-9 [CrossRef]
- Hunt A, Rowe N, Lam A, Martin F. Outcomes in persistent hyperplastic primary vitreous. Br J Ophthalmol. 2005;89:859–863. doi:10.1136/bjo.2004.053595 [CrossRef]
- Sun MH, Kao LY, Kuo YH. Persistent hyperplastic primary vitreous: magnetic resonance imaging and clinical findings. Chang Gung Med J. 2003;26:269–276.
- Müllner-Eidenböck A, Amon M, Moser E, Klebermass N. Persistent fetal vasculature and minimal fetal vascular remnants: a frequent cause of unilateral congenital cataracts. Ophthalmology. 2004;111:906–913. doi:10.1016/j.ophtha.2003.07.019 [CrossRef]
- Alexandrakis G, Scott IU, Flynn HW Jr, Murray TG, Feuer WJ. Visual acuity outcomes with and without surgery in patients with persistent fetal vasculature. Ophthalmology. 2000;107:1068–1072. doi:10.1016/S0161-6420(00)00100-7 [CrossRef]
- Asbell PA, Chiang B, Somers ME, Morgan KS. Keratometry in children. CLAO J. 1990;16:99–102.
|Complaint||No. of Patients (%)|
|White reflex||60 (78.9%)|
|Small eye||18 (23.6%)|
|Squeezing the affected eye||12 (15.7%)|
|Defective vision||11 (14.4%)|
Etiology of Cataract
|Etiology||No. of Patients (%)|
|Persistent fetal vasculature||21 (27.63%)|
|Preexisting posterior capsular defect||8 (10.5%)|
|Posterior lenticonus||2 (2.6%)|
|Characteristic||Control Group||Persistent Fetal Vasculature Group||Pa|
| Male||34 (61.8%)||16 (76.2%)|
| Female||21 (38.1%)||5 (23.8%)|
| Right eye||29 (52.72%)||8 (38.09%)|
| Left eye||26 (47.27%)||13 (61.9%)|
| Total||21 (38.1%)||11 (52.4%)|
| Mixed||13 (23.6%)||–|
| Posterior capsular plaque||12 (21.8%)||10 (47.6%)|
| Zonular||3 (5.4%)||–|
| Nuclear||1 (1.8%)||–|
| Membranous/partially absorbed||1 (1.8%)||–|
| Anterior capsular||4 (7.2%)||–|