Purpose
To compare the demographic and clinical distribution of primary and secondary congenital glaucoma from a registry at King Khaled Eye Specialist Hospital.
Design
Registry-based cohort study.
Methods
Review of registry data that included new patients with congenital glaucoma seen between 2001 and 2003 (29 months); analysis of the demographic data and clinical features of primary and secondary congenital glaucoma at presentation.
Results
A total of 325 eyes of 180 patients were included. Most patients had primary congenital glaucoma (80%). The mean (± SD) age at presentation for primary congenital glaucoma was 3.8 ± 10.7 months and for secondary congenital glaucoma was 4.3 ± 7.9 months. Most primary congenital glaucoma and secondary congenital glaucoma patients had bilateral disease (82.6%; 74.3%). Primary congenital glaucoma was equally distributed by sex but secondary congenital glaucoma was 1.5-fold more common in male patients. A positive family history was elicited in 30%, and almost 60% had a history of consanguinity in both groups. The mean intraocular pressure and corneal diameter were comparable in both groups but the axial length was significantly longer in primary congenital glaucoma and cup-to-disc (C/D) ratio greater in secondary congenital glaucoma. In the primary congenital glaucoma group, corneal haze showed a significant relationship with most clinical parameters. In primary congenital glaucoma, a positive correlation was noted between age at presentation and increasing corneal diameter and axial length but a negative relationship was noted with C/D ratio and corneal haze, whereas for secondary congenital glaucoma only axial length was positively correlated.
Conclusion
The congenital glaucoma registry provides unique baseline data on primary congenital glaucoma and secondary congenital glaucoma in Saudi Arabia that will enable us to better understand the disease in the Kingdom and region.
Congenital glaucoma is a developmental disorder characterized by elevated intraocular pressure (IOP), corneal edema, enlargement of the globe (buphthalmos), increased corneal diameter, Haab striae, and optic nerve damage. Congenital glaucoma can be classified into primary congenital glaucoma or secondary congenital glaucoma. Primary congenital glaucoma is typically recognized at birth or in early childhood and has no associated ocular or systemic abnormalities. Secondary forms of congenital glaucoma typically have an identified mechanism of glaucoma and are associated with a range of ocular and/or systemic abnormalities.
The prevalence of congenital glaucoma varies widely, with high prevalence noted in Slovakian Gypsies, in Saudis, and in Southern India. Most studies on congenital glaucoma address the distribution of primary congenital glaucoma, secondary congenital glaucoma, and acquired glaucomas combined as a group under the umbrella of childhood glaucoma. However, the distribution of primary and secondary congenital glaucoma in a large series has not been addressed in patients with congenital glaucoma in the Middle East.
This study interrogated the congenital glaucoma registry at the King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia to determine the demographic and clinical characteristics of primary and secondary congenital glaucoma that presented to the hospital between 2001 and 2003. King Khaled Eye Specialist Hospital is a major eye care provider in the kingdom that receives referred patients with congenital glaucoma from all Saudi regions and surrounding Gulf states.
Methods
The congenital glaucoma registry was maintained at King Khaled Eye Specialist Hospital between 2001 and 2003 over a 29-month period. Data collection following this period was discontinued. The registry included demographic and clinical information of all new patients with congenital glaucoma. These newly diagnosed patients were referred through the Ministry of Health Saudi Arabia or physicians in the community, or presented at the screening clinic or emergency room of the hospital. Children with aphakic glaucoma, traumatic glaucoma, uveitic glaucoma, and other acquired glaucomas in children were excluded. Congenital glaucoma was defined as those with IOP >21 mm Hg combined with associated signs such as globe enlargement (buphthalmos), enlarged corneal diameter (11 mm in newborns, 12 mm or greater in a child), corneal haze, Haab striae, and increased axial length.
Primary congenital glaucoma was defined as glaucoma that was potentially genetically inherited and encompassed those glaucomas that presented at birth, in infancy, or early in childhood. These individuals had no associated ocular or systemic anomalies. Patients with secondary congenital glaucoma were defined as those with associated ocular or systemic anomalies.
A data collection sheet developed for the registry was used to collect clinical information and data were entered into a database by a clinical coordinator supervised by a physician. The patient demographic and baseline clinical indices obtained at the initial visit were recorded. These data included: age, sex, nationality, province or location of the family, laterality of the disease, age at presentation, family history, and consanguinity. Consanguinity was defined as a relationship by blood where the parents or grandparents were first- or second-degree cousins. The clinical data were obtained mostly at the first examination under either sedation or anesthesia. IOP was measured by Tonopen (Reichert Technologies, Depew, New York, USA) and/or pneumatonometer (Reichert Technologies) in younger children, with some readings by Goldmann tonometry in older children. When IOP was obtained under sedation or anesthesia, it was always measured within the first few minutes after the child was asleep. Corneal diameter, corneal haze (discussed below), Descemet membrane breaks, iris and anterior chamber alterations, lens changes, cup-to-disc ratio (C/D), axial length, and lens thickness were typically recorded by the physician at the time of surgery. Fundus examination was performed during initial examination under anesthesia or at the first examination under sedation if the cornea was cloudy. The C/D and data obtained preoperatively and postoperatively were analyzed separately and compared. Visual acuity was recorded at the first visit or during the hospital stay after surgery. Associated ocular and systemic anomalies were also noted.
Corneal haze was graded as mild, moderate, or severe based on whether the structures of the anterior segment were visible at the initial examination under anesthesia prior to surgery. Mild haze was defined as when the anterior segment structures could be clearly identified in presence of haze, moderate haze as where the structures could be seen but details of anterior segment structures could not be clearly delineated, and severe haze as when the view to the anterior chamber was completely obstructed by corneal haze or scarring.
In this study, anterior segment dysgenesis was defined as a condition where anomalies of the anterior segment that included the cornea, iris, angle, and the lens were seen that did not fit into any of the classic syndromes, such as Peter anomaly and the Axenfeld-Rieger disease spectrum. The findings included a spectrum and a combination of changes that included congenital corneal opacification, iris atrophy, partial aniridia, ectropion uvea, and lens opacities. Cases labeled as unclassified were those in which the patient had glaucoma with a combination of ocular anomalies and systemic abnormalities that did not fit the description of known syndromes associated with congenital glaucoma.
The data were reviewed for quality and any conflict and/or incomplete data were either corrected or excluded. For example, data on lens thickness and Descemet membrane breaks were incomplete and were excluded in the analysis. Visual acuity data were obtained but were excluded from analysis as the recording was largely subjective in the children, who were largely nonverbal.
Institutional review board (IRB) approval was obtained from the Human Ethics Committee/IRB at the King Khaled Eye Specialist Hospital to analyze registry data. This approval was obtained prior to the data analysis.
Data Analysis
All data were entered and managed using a Microsoft Access database. Data analysis was conducted using SPSS version 19.0 by IBM (SPSS Inc, Chicago, Illinois, USA), Medcalc 11.6 (MedCalc Software, Mariakerke, Belgium), and Statpac 11.0 (StatPac Inc, Bloomington, Minnesota, USA). Student t test was used to compare means across groups in case of continuous variables, and χ 2 test and comparison of proportions were used (Fisher exact test when indicated) to compare groups. A P value <.05 was considered statistically significant.
Results
A total of 325 eyes of 180 patients were entered into the registry between 2001 and 2003.Of the 180 patients, the majority (144 [80%; 95% CI: 74.16-85.84]) were diagnosed with primary congenital glaucoma while only 36 (20%; 95% CI: 14.16-25.84) were diagnosed with secondary congenital glaucoma ( Table 1 ).
| Variable | PCG (N = 144) | SCG (N = 36) | Total PCG + SCG | P Value |
|---|---|---|---|---|
| Age at presentation [range] | 3.8 (± 10.7) mo [1d-72 mo] | 4.3 (± 7.9) mo [1d-36 mo] | 3.9 (± 10.3) mo [1d-72 mo] | .775 |
| Sex, n (%) | ||||
| Male | 70 (48.6%) | 22 (61.1%) | 92 (51.1%) | .179 |
| Female | 74 (51.4%) | 14 (36.9%) | 88 (48.9%) | |
| Laterality, n (%) | ||||
| Unilateral | 25 (17.4%) | 10 (27.8%) | 35 (19.4%) | .158 |
| Bilateral | 119 (82.6%) | 26 (72.2%) | 145 (80.6%) |
The mean (± SD) age at presentation for the total sample was 3.9 ± 10.3months (range: 1 day to 72 months). Eyes with primary congenital glaucoma presented slightly earlier than those with secondary congenital glaucoma: primary congenital glaucoma 3.8 ± 10.7 months (range: 1 day to 72 months) vs secondary congenital glaucoma 4.3 ± 7.9 months (range: 1 day to 36 months). However, this difference was not statistically significant ( P = .775). Meanwhile, the majority of subjects (n = 145; 80.6%) in both the primary and secondary congenital glaucoma groups had bilateral disease. Additionally, among those with primary congenital glaucoma 119 (119/144; 82.6%) were bilateral, whereas among the secondary congenital glaucoma cases 26 (26/36; 72.2%) had bilateral disease. This small difference was statistically insignificant ( P = .158).
The overall sex distribution was fairly similar between male (51.1%; n = 92) and female patients (48.9%; n = 88). In the primary congenital glaucoma group female subjects (74/144; 51.4%) were slightly more affected than male subjects (70/144; 48.6%). In contrast, secondary congenital glaucoma was more common in male (22/36; 61.1%) than in female subjects (14/36; 38.9%); however, these differences were not statistically significant ( P = .179) ( Table 1 ).
Fifty-four patients in the entire sample (54/180; 30%) had a positive family history, with a similar proportion among primary and secondary congenital glaucoma patients. In the primary congenital glaucoma group a positive family history was elicited in 29.9% (43/144), whereas in the secondary congenital glaucoma group the proportion was 30.6% (11/36) ( P = .935).
Consanguinity was recognized among 106 of 180 (58.9%) patients: 85 of 144 (59%) primary congenital glaucoma patients and 21 of 36 (58.3%) secondary congenital glaucoma patients ( P = .939). Additionally, most of the patients in this registry were of Saudi nationality (164/180; 91.1%). The residence of these patients was concentrated among 3 of 5 regions of Saudi Arabia ( Table 2 ). The distribution of cases was higher among the south, central, and west regions than among the east and north regions, where such difference in distribution among the 5 major regions was statistically significant ( P = .0003).
| Region | PCG N (%) | SCG N (%) | Total Region N (%) |
|---|---|---|---|
| Central | 32 (22.2) | 9 (25) | 41 (22.8) |
| North | 13 (9) | 2 (5.6) | 15 (8.3) |
| South | 40 (27.8) | 4 (11.1) | 44 (24.4) |
| West | 34 (23.6) | 6 (16.7) | 40 (22.2) |
| East | 16 (11.1) | 8 (22.2) | 24 (13.3) |
| Total Saudis | 135 (93.8) | 29 (80.6) | 164 (91.1) |
| Total non-Saudis | 9 (6.2) | 7 (19.4) | 16 (8.9) |
| Grand total | 144 (100) | 36 (100) | 180 (100) |
The causes of secondary congenital glaucoma are summarized in Table 3 . The more common causes of secondary congenital glaucoma included Peter anomaly (8/36; 22.2%), anterior segment dysgenesis (6/36; 16.7%), aniridia/Riegers syndrome (5/36; 13.9%), and microphthalmia (3/36; 8.3%).
| Secondary Diagnosis (Major Cause) | Patients | Percent |
|---|---|---|
| Anterior segment dysgenesis | 6 | 16.7 |
| Peter anomaly | 8 | 22.2 |
| Aniridia/Rieger syndrome | 5 | 13.9 |
| Microphthalmia | 3 | 8.3 |
| Iris/chorioretinal coloboma | 2 | 5.6 |
| Down syndrome | 1 | 2.8 |
| Rubella syndrome | 1 | 2.8 |
| Cataract | 2 | 5.6 |
| Klippel-Trenaunay-Weber syndrome | 2 | 5.6 |
| Total RD/PHPV | 1 | 2.8 |
| Retinopathy of prematurity | 1 | 2.8 |
| Unclassified | 4 | 11.1 |
| Total | 36 | 100.0 |
The clinical findings are summarized in Table 4 . The mean (± SD) IOP for all patients with congenital glaucoma at baseline was 25.9 ± 7.5 mm Hg (median 25 mm Hg, range: 11-60 mm Hg), and corneal diameter was 12.5 ± 1.6 mm (median 12.5 mm, range: 5-18.5 mm). The mean IOP at presentation, corneal diameter, and C/D ratio in primary and secondary congenital glaucoma eyes were comparable.
| Variable | PCG Mean (± SD) | SCG Mean (± SD) | Mean Values of Total Sample | P Value |
|---|---|---|---|---|
| IOP (mm Hg) | 25.9 (± 7.5) | 26.5 (± 7.9) | 25.9 (± 7.5) | .665 |
| Corneal diameter (mm) | 12.6 (± 1.3) | 12 (± 2.4) | 12.5 (± 1.6 ) | .131 |
| C/D (H) | 0.42 (± 0.38) | 0.55 (± 0.36) | 0.45 (± 0.38) | .047 a |
| C/D (V) | 0.55 | 0.75 | 0.61 (± 0.33) | .002 a |
| Axial length (mm) | 22.6 (± 2.9) | 19.5 (± 2.2) | 21.2 (± 3.0) | .012 a |
a Significant P value (indicating differences between primary and secondary congenital glaucoma).
The C/D ratio was assessed preoperatively in 101 eyes and only postoperatively in 51 eyes. The average C/D in eyes assessed preoperatively was 0.69 ± 0.19 and in those assessed only in the postoperative period was 0.69 ± 0.27. There were no differences in the C/D whether assessed preoperatively or in the immediate postoperative period. There were 133 eyes that had C/D assessments performed both in the preoperative period and at the 3-month postoperative visit. In these eyes the C/D ratio preoperatively was 0.68 ± 0.21 and postoperatively 0.75 ± 0.25. These differences were not statistically significant. Disc examination was not performed in 40 eyes mainly because of poor view to the posterior segment in the immediate postoperative period. Both horizontal and vertical C/D ratios were significantly larger in secondary congenital glaucoma eyes when compared with primary congenital glaucoma eyes.
The mean (± SD) axial length in primary congenital glaucoma eyes was 22.6 ± 2.9 mm (range 18.3-26.7 mm), whereas in secondary congenital glaucoma it was 19.5 ± 2.2 mm (range 16.3-23.6 mm). The mean axial length of primary congenital glaucoma eyes was significantly longer than secondary congenital glaucoma eyes ( P = .012) ( Table 4 ).
Table 5 summarizes the degree of corneal haze in primary and secondary congenital glaucoma. Mild to moderate haze was noted in 168 of 263 eyes (63.9%) in the primary congenital glaucoma group and in 34 of 62 eyes (54.8%) in the secondary congenital glaucoma group. Severe haze was seen in 32 of 263 primary congenital glaucoma eyes (12.2%) and 14 of 62 secondary congenital glaucoma eyes (22.6%). In eyes with primary congenital glaucoma, corneal haze showed a significant correlation with IOP, corneal diameter, and C/D ratio but not with axial length. However, in secondary congenital glaucoma eyes, corneal haze (eyes with corneal edema and/or opacity) showed a significant correlation only with horizontal C/D ratio ( Table 6 ).
| Degree of Haze | PCG N (%) | SCG N (%) | Total N (%) |
|---|---|---|---|
| Clear | 52 (19.8) | 8 (12.9) | 60 (18.5) |
| Mild | 139 (52.9) | 19 (30.6) | 158 (48.6) |
| Moderate | 29 (11) | 15 (24.2) | 44 (13.5) |
| Severe | 32 (12.2) | 14 (22.6) | 46 (14.2) |
| Undocumented | 11 (4.2) | 6 (9.7) | 17 (5.2) |
| Total | 263 (100) | 62 (100) | 325 (100) |
| Correlated Variables | PCG | SCG | ||
|---|---|---|---|---|
| R | P Value | R | P Value | |
| Age of presentation vs IOP | −0.086 | .256 | 0.057 | .735 |
| Age of presentation vs corneal diameter | 0.15 | .039 a | −0.067 | .68 |
| Age of presentation vs horizontal C/D | −0.29 | <.0001 a | −0.017 | .917 |
| Age of presentation vs vertical C/D | −0.37 | .003 a | 0.11 | .585 |
| Age of presentation vs axial length | 0.84 | .001 a | 0.641 | .046 a |
| Age of presentation vs corneal haze | −0.280 | <.0001 a | −0.09 | .510 |
| Degree of haze vs IOP | 0.25 | .001 a | 0.034 | .837 |
| Degree of haze vs corneal diameter | 0.19 | .007 a | 0.12 | .444 |
| Degree of haze vs horizontal C/D | 0.45 | <.0001 a | 0.41 | .007 a |
| Degree of haze vs vertical C/D | 0.4 | .001 a | 0.26 | .21 |
| Degree of haze vs axial length | −0.48 | 0.111 | −0.06 | .875 |
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