Evolution of central corneal thickness in children with congenital glaucoma requiring glaucoma surgery

Factors and outcomes associated with corneal edema and Haabs striae in primary congenital glaucoma

PURPOSE

To identify specific factors and outcomes associated with corneal edema and Haabs striae in primary congenital glaucoma (PCG).

METHODS

The medical records of patients with PCG from 2011 to 2023 with >3 months' follow-up were reviewed retrospectively. Preoperative details and final outcomes were compared between eyes with and without corneal findings. The right eye of bilateral cases and the affected eye in unilateral cases were included.

RESULTS

A total of 58 patients (104 eyes, 69% male) underwent initial angle surgery at an average age of 297 ± 368 (median, 134) days. Corneal edema and Haabs striae were present preoperatively in 72 (69%) eyes of 41 patients and 68 (65%) eyes of 39 patients, respectively. Patients with corneal edema presented at a younger age (P < 0.0001) and with shorter axial length (P = 0.01) than those without edema. Univariate analysis showed that corneal edema was associated with worse visual acuity at final follow-up (OR = 4.4; 95% CI, 1.2-25.3). Patients with Haabs striae were older than those without striae (P = 0.04). After angle surgery, corneal edema was present at 1 month in 71% (95% CI, 52-84), at 2 months in 26% (95% CI, 12-42), at 3 months in 16% (95% CI, 6-30), and at 1 year in 3% (95% CI, 0-13). Corneal opacification did not resolve in 4 eyes of 3 patients after >4 years of follow-up.

CONCLUSIONS

In our study cohort, corneal edema resolved in the majority of PCG cases within 2-3 months of initial angle surgery but was associated with younger age at presentation and worse visual acuity at final follow-up.

Primary congenital glaucoma: An iridotrabeculodysgenesis?

PURPOSE

To analyze primary congenital glaucoma (PCG) anterior chamber and angle anomalies over 360° as possible biomarkers of severity and prognosis.

METHODS

A cross-sectional observational study was conducted analyzing anterior segment anomalies of PCG patients over 4 years of age who underwent trabeculectomy combined with trabeculotomy and age-matched controls using anterior segment optical coherence tomography (ASOCT), CASIA-2. Anterior iridotrabecular adhesions or anterior iris insertion was identified and quantified from the scleral spur using the iridotrabecular contact (ITC) index parameter as a surrogate.

RESULTS

There was a variable but significantly increased anterior iridotrabecular adhesion on ITC index, ITC area, corneal volume, anterior chamber volume, iris volume, anterior chamber depth, and small/absent trabecular meshwork in PCG eyes compared to control eyes. In PCG eyes, anterior iridotrabecular adhesion had a positive correlation with pre-operative central corneal thickness (CCT) (r = 0.53, P = 0.02), review iris thickness (r = 0.4, P = 0.04), and ITC area (r = 0.85, P < 0.001). Review iris thickness had a negative correlation with pre-operative vertical cup-disc ratio (r = -0.51, P = 0.008). Iris hypoplasia with fewer or absent folds, collarette, pupillary ruff, and pupillary ruff to collarette distance was significantly different from controls.

CONCLUSION

ASOCT in PCG eyes has shown that they have variable anterior iridotrabecular tissue adhesions, anomalous tissue/membranes in the angle, and iris hypoplasia correlating with pre-operative cup-disc ratio. These features could be used as gonioscopic and clinical biomarkers to assess the severity and prognosis of the disease. The presence of abnormal iris morphology and iridotrabecular tissue anomalies in PCG suggests that it is more than just isolated trabeculodysgenesis and is probably best considered as part of the anterior segment dysgenesis spectrum.

Ultrasound biomicroscopy of the anterior segment in patients with primary congenital glaucoma: a review of the literature

PURPOSE

Primary congenital glaucoma (PCG) is a form of childhood glaucoma caused by maldevelopment of the anterior chamber. Disease severity differs greatly amongst patients. Ultrasound biomicroscopy (UBM) is a non-invasive technique that can visualize the anterior segment in infants in vivo. The purpose of this narrative review is to make an overview of the UBM data in PCG and study the applicability of UBM in characterizing the disease.

METHODS

An online search was performed on PubMed in December 2020. After a critical appraisal of the included articles, study and patient characteristics were summarized. The UBM measurements of the anterior segment in PCG of the different studies were analysed.

RESULTS

Six studies were included in this review. All were cross-sectional prospective studies. A total of 221 PCG eyes were examined. PCG eyes showed a larger trabecular iris angle, decreased iris thickness, narrower or absent Schlemm's canal and an increased zonular length compared to controls. Abnormal tissue membrane covering the trabecular meshwork and abnormal insertion of the iris and ciliary process were frequently found. The success rate of glaucoma surgery depended on the severity of anterior segment malformations found with UBM.

CONCLUSION

Malformations of the anterior segment in PCG can be demonstrated by UBM in vivo. This imaging can help to characterize disease severity and might support surgical treatment decisions.

Disease-related and age-related changes of anterior chamber angle structures in patients with primary congenital glaucoma: An in vivo high-frequency ultrasound biomicroscopy-based study

OBJECTIVES

To provide in vivo measurements of anterior chamber angle structures and their relationship with age as evaluated by high-frequency ultrasound biomicroscopy (UBM) in patients with primary congenital glaucoma (PCG).

METHODS

High-frequency UBM was done for 51 PCG eyes from 40 patients (aged from 3 to 96 months) and 11 unaffected contralateral eyes. Parameters, including the proportion of observable abnormal tissue membrane and Schlemm's canal, the largest cross-sectional area (CSA) of Schlemm's canal (SC), SC meridional diameter, trabecular-iris angle (TIA), trabecular meshwork (TM) thickness, iris thickness, ciliary process length, and corneal limbus thickness were compared between the two groups and their relationship with age was explored in PCG eyes.

RESULTS

Abnormal tissue membrane was detected in 27.5% of PCG eyes and none in unaffected eyes. SC was observed in 73.1% of PGC eyes compared to 100% in unaffected eyes (P<0.001). The largest CSA of SC, SC meridional diameter, iris thickness, and corneal limbus thickness were all significantly smaller in PCG eyes compared to unaffected eyes (all P<0.05). TIA and ciliary process length in unaffected eyes were smaller than PCG eyes (both P<0.05). The largest CSA of SC, TM thickness, iris thickness, and ciliary process length were all significantly correlated to age in PCG eyes (P<0.05).

CONCLUSIONS

The anatomical information evaluated by high-frequency UBM may provide glaucoma specialists a useful tool to aid in understanding the dysgenesis and changes with age of anterior chamber angle in PCG.

Long-term surgical outcomes of ab externo trabeculotomy in the management of primary congenital glaucoma

PURPOSE

To analyze the long-term results of ab externo trabeculotomy with a Harms trabeculotome at a single, tertiary care pediatric hospital.

METHODS

The medical records of pediatric patients operated on between September 2006 and June 2018 were reviewed retrospectively. Kaplan-Meier analysis was performed, with success defined as postoperative intraocular pressure (IOP) of ≤21 mm Hg, >20% reduction from preoperative IOP, and no need for further glaucoma surgery. Risk factors for failure were identified using Cox proportional hazards ratio.

RESULTS

A total of 63 eyes of 40 patients were included. The cumulative probability of success rate was 83% at 3 months, 76% at 6, 73% at 12, 72% at 18, and 65% at final visit. Presentation within 3 months of life was associated with a less favorable outcome. Thirty-five eyes (56%) underwent repeat trabeculotomy to treat a different area of the trabecular meshwork because of inadequately controlled IOP after the first session. Of those who needed another session of trabeculotomy, the final success rate was 60.2%. IOP significantly decreased from 29.79 ± 7.67 mm Hg at baseline to 16.13 ± 3.41 mm Hg by final follow-up (P = 0.001). Patients were followed for an average of 85.74 ± 32.95 months. IOP and success rates remained stable 18 months after surgery.

CONCLUSIONS

In our patient cohort, ab externo trabeculotomy was associated with good long-term results. More extensive trabeculotomy (ie, more than one procedure) was associated with better long-term success rates.

Assessment of the anterior segment of patients with primary congenital glaucoma using handheld optical coherence tomography

PURPOSE

To investigate the potential of handheld optical coherence tomography (HH-OCT) in assessing the anterior segment of the eye in patients with primary congenital glaucoma.

DESIGN

A prospective, case-controlled observational study.

PARTICIPANTS

Twenty-two patients with primary congenital glaucoma (PCG, 9 females and 13 males; mean age 4.36 ± 3.4 years) and age-, gender- and ethnicity-matched healthy participants.

METHODS

Anterior OCT was performed in all participants using a high-resolution HH SD-OCT device (Envisu 2300, Leica Microsystems, Germany) without anaesthesia or sedation.

RESULTS

Anterior HH-OCT in PCG visualised Haab's striae in 14.3%, uneven internal cornea in 9.5% and epithelial thickening in 11.9% of patients with central corneal thickening (CCT, p < 0.001). CCT was significantly correlated with the intraocular pressure (IOP, p < 0.001). The flat iris with a thin collarette zone was found in 59.5%, anterior iris insertion in 11.90% of eyes affected by PCG. Two independent examiners showed sensitivity and specificity of 87% and 77%, respectively, by instating iris thinning and flattening of the anterior profile.

CONCLUSIONS

Anterior HH-OCT has significant potential to improve diagnosis and management of PCG. Clinically relevant information can be obtained non-invasively and without sedation. High specificity makes anterior HH-OCT an important adjunct for management of PCG. Excellent visualisation of the iris insertion on OCT indicates potential for AS OCT to assist with surgical planning, including decision on the type of surgery and location of the incision.

Features of measurement of intraocular pressure in children

This review discusses the results of various studies conducted in recent years on the comparison of modern methods of measuring intraocular pressure (IOP) in children: pneumotonometry, Maklakov applanation tonometry, and tonometry using Perkins tonometer, Goldmann tonometer, Icare tonometer, Ocular Response Analyzer, TonoPen handheld tonometer, transpalpebral tonometer TIOP01, or a dynamic contour Pascal tonometer. This study discusses the advantages and disadvantages of different methods of measurement of IOP in children, including the evaluation of patients with fibrous lens capsules that might affect the measurement of IOP and an analysis of the characteristics of evaluation of IOP in children with congenital glaucoma.

Longitudinal evaluation of central corneal thickness in congenital glaucoma

PURPOSE

To assess the central corneal thickness in primary congenital glaucoma before and after surgical treatment and compare it with a normal population.

METHODS

We conducted a longitudinal analysis of primary congenital glaucoma patients, in whom we measured central corneal thickness before and after treatment (Group 1). We compared our results with a normal population (Group 2), who underwent ophthalmological examination under anesthesia for other reasons.

RESULTS

Mean age (months) in Group 1 (N=23) and Group 2 (N=40) at the time of the first exam was 5.5 and 9.2 (P=0.004), respectively. Mean central corneal thickness (microns) in Group 1 was: 663 before treatment and 557 after treatment (P<0.001). In Group 2, mean central corneal thickness (microns) was 551. Comparisons show statistical difference between mean values before and after treatment (P<0.001), but not between post-treatment CCT mean values in Group 1 and mean CCT values in Group 2 (P=0.627).

CONCLUSION

In primary congenital glaucoma, central corneal thickness values show unique peculiarities. They are higher than normal before treatment (thicker corneas), due to corneal edema caused by elevated intraocular pressure. After surgical treatment, central corneal thickness measurements decrease toward the mean values for the normal population.

Intraocular pressure measurement by three different tonometers in primary congenital glaucoma

Purpose:

To determine the agreement between intraocular pressure (IOP) measurements using an automated non-contact tonometer (NCT), Goldmann applanation tonometer (GAT), and the ocular response analyzer (ORA) in subjects with primary congenital glaucoma (PCG).

Methods:

Twenty-nine eyes of 17 PCG patients underwent IOP measurements using NCT, GAT and ORA. Variables obtained by the ORA were corneal-compensated IOP (IOPcc), Goldmann-correlated IOP (IOPg), corneal hysteresis (CH), and corneal resistance factor (CRF). A difference more than 1.5 mmHg for IOP was considered as clinically relevant.

Results:

Mean age of the patients was 12 years. Mean IOP (±standard deviation, SD) was 15.3 ± 2.8 mmHg (GAT), 15.5 ± 6.0 (NCT), 19.2 ± 7.0 (IOPg), and 21.1 ± 7.9 (IOPcc); (P = 0.001). Except for NCT vs. GAT (P = 1.0), the average IOP difference between each pair of measurements was clinically relevant. The 95% limits of agreements were − 10.2 to 10.3 mmHg (NCT vs. GAT), −7.8 to 15.3 (IOPg vs. GAT), and − 8.1 to 19.0 (IOPcc vs. GAT). The differences in IOP measurements increased significantly with higher average IOP values (r = 0.715, P = 0.001, for NCT vs. GAT; r = 0.802, P < 0.001, for IOPg vs. GAT; and r = 0.806, P < 0.001, for IOPcc vs. GAT). CH showed a significant association with differences in IOP measurements only for IOPcc vs. GAT (r = 0.830, P < 0.001).

Conclusion:

Mean IOP obtained by NCT was not significantly different from that of GAT, but ORA measured IOPs were significantly higher than both other devices.

Ultrasound biomicroscopy as a diagnostic tool in infants with primary congenital glaucoma

Purpose

Studying the role of ultrasound biomicroscopy (UBM) in detection of anterior segment changes in infants with primary congenital glaucoma (PCG).

Methods

Cross-sectional study that included 25 eyes of 15 patients suffering from PCG and a control group of 15 eyes of ten age- and sex-matched participants. Diagnosis of PCG was based on clinical data (intraocular pressure, corneal diameter, fundus examination and amplitude-modulation scan measurement of axial length). UBM examination was done for all participants for measurement of central corneal thickness, anterior chamber depth, lens thickness, iris thickness (measured 2 mm from the iris root and again at the thickest point near the pupil), zonular length, posterior chamber depth, and angle of anterior chamber. Qualitative evaluation was done for abnormal angle membranes, iris insertion level, and ciliary processes position and configuration.

Results

Mean age ± standard deviation was 10.32±3.59 months in the study group and 14.54±5.9 months in the control group. The central corneal thickness, anterior chamber depth, zonular length, and angle of anterior chamber were significantly larger in the study group than in the control group, with mean values 700±190 μm, 3.55±0.32 mm, 1.02±0.15 mm, and 58.47°±5.57°, respectively. The posterior chamber depth had a mean of 0.33±0.06 mm, which was significantly smaller than that of the control group. In the study group, the mean iris thickness 2 mm from the iris root was 0.32±0.04 mm, the mean iris thickness at the thickest point near the pupil was 0.38±0.08 mm, and the mean lens thickness was 3.32±0.18 mm. These three parameters were smaller than the control group but the difference was insignificant. Loss of normal iris configuration was detected in all eyes of the study group. Anterior iris insertion was detected in 56% of the eyes in the study group, and abnormal angle membrane was found in 12%.

Conclusion

UBM is a useful tool for detection of anterior segment changes in PCG, which is helpful especially in cases with opaque cornea or cases with borderline clinical findings.

Central corneal thickness in children and adolescents with pediatric glaucoma and eye disorders at risk of developing glaucoma

BACKGROUND

To investigate central corneal thickness (CCT) in children with glaucoma and at risk for glaucoma.

METHODS

The study included 139 children with glaucoma: 66 at risk for glaucoma (ie, aphakia, aniridia, or uveitis) and 66 normal children. CCT was measured by ultrasound pachymetry and intraocular pressure (IOP) by applanation. Analysis of variance was used to compare CCT between groups. Correlation analysis assessed associations between CCT and ocular factors including spherical equivalent, cup-to-disc ratio, glaucoma medications, and number of intraocular surgeries.

RESULTS

CCT was significantly higher for 141 eyes with glaucoma (mean: 0.598 mm, P < .001) and 76 eyes at risk for glaucoma (mean: 0.604 mm, P = .001) than for 66 normal eyes (mean: 0.558 mm). No significant difference was observed between at-risk (P = .989) and glaucoma eyes. Eyes with aphakia (0.653 mm) and aniridia (0.639 mm) had the thickest CCT values. Thinnest CCT was found in anterior segment dysgenesis and uveitis (mean: 0.541 mm). A significant positive correlation between CCT and spherical equivalent was found for glaucoma (r = 0.413; P < .001) and at-risk (r = 0.412; P < .0003) eyes, and between CCT and intraocular surgery for at-risk eyes (P = .0066). A significant negative correlation was found between CCT and cup-to-disc ratio for glaucoma eyes (r = -0.223; P = .01).

CONCLUSION

This is the largest series of CCT in pediatric glaucoma and related disorders. The data suggest caution in application of standard formulas for IOP-to-CCT correction when evaluating children with glaucoma because their mean CCT values extend far beyond values reported for normal eyes.