Pediatric intraocular pressure measurements: Tonometers, central corneal thickness, and anesthesia

Transconjunctival XEN45 implantation for secondary open-angle glaucoma management in a pediatric patient with WAGR syndrome

Purpose

To report a case of XEN45 gel stent implantation in a pediatric patient with WAGR syndrome as a successful surgical intervention in the management of multifactorial secondary open-angle glaucoma.

Observations

A 6-year-old female with a history of WAGR syndrome, bilateral congenital aniridia, pseudophakia OD and glaucoma OD, was referred for a XEN45 gel stent OD. IOP was persistently elevated at 24 mm Hg despite two glaucoma medications. Implantation of the XEN45 gel stent was performed using a transconjunctival ab externo approach. There were no significant intra-or-postoperative adverse events associated with the stent. The patient achieved good IOP-lowering control without glaucoma medications across the 18-month follow-up period.

Conclusions

A XEN45 stent through a transconjunctival ab externo approach may be an effective surgical intervention in pediatric patients with secondary open-angle glaucoma associated with aniridia and aphakia.

Effect of neck extension on intraocular pressure in paediatric patients undergoing palatoplasty

BACKGROUND

Intraocular pressure (IOP) can increase with postural changes, which can cause ocular complications. Neck extension is commonly used during palatoplasty to improve surgical angulation. This study evaluates whether neck extension affects IOP during palatoplasty.

METHODS

In this prospective observational study, IOP was measured using a rebound tonometer at four specific time points: T1, 10 min after anaesthesia while in the supine position; T2, 5 min after neck extension; T3, at completion of palatoplasty with neck extended; and T4, 5 min after returning to the supine position. The primary outcome was the IOP at T2, and the secondary outcomes were the IOPs at T3 and T4. Haemodynamic and respiratory variables were also measured at each time point.

RESULTS

Thirty-seven patients were included. IOP at T2 was significantly higher than at T1 (15.8 ± 3.4 mmHg vs 10.5 ± 2.8 mmHg, P < 0.001), and IOPs at T3 and T4 were also significantly higher than at T1 (T3 vs T1: 18.9 ± 3.6 mmHg vs 10.5 ± 2.8 mmHg, P < 0.001; T4 vs T1: 13.3 ± 3.7 mmHg vs 10.5 ± 2.8 mmHg, P < 0.001). However, no significant differences were observed for the haemodynamic and respiratory variables at any time point.

CONCLUSION

Our findings indicate that the intraoperative neck extension position during palatoplasty significantly increases IOP in paediatric cleft palate patients undergoing a palatoplasty.

Lenstar LS900 vs EchoScan US-800: comparison between optical and ultrasound biometry with and without contact lenses and its relationship with other biometric parameters

BACKGROUND

Due to the increasing use of contact lenses (CL) and the interest in ocular and body size relationships, this study aimed to compare measurements from two biometers (contact ultrasonic EchoScan US-800 and non-contact optical Lenstar LS900) with and without CL and to explore the relationship between ocular and body biometric parameters.

DESIGN AND METHODS

This cross-sectional study measured ocular biometry using two biometers along with their body height and right foot length in 50 participants. Differences between biometry data from the two devices were compared and correlations between ocular and body biometric values were analyzed.

RESULTS

All parameters showed interbiometric differences (p ≤ 0.030), except crystalline lens thickness during CL wear (p = 0.159). Comparing measurements with and without CL, differences were observed in axial length (p < 0.001), vitreous length measured by optical biometer (p = 0.016), and anterior chamber depth by ultrasonic biometer (p < 0.016). Lens thickness remained unaffected (p ≥ 0.190). Body height and foot length were correlated with anterior chamber depth, vitreous length, and axial length (p ≤ 0.019, r ≥ 0.330). Most biometric parameters were correlated among them using both devices (p ≤ 0.037, r ≥ 0.296).

CONCLUSIONS

These biometers are not interchangeable and CL affects measurements. Body height and foot length correlate with ocular dimensions, and most ocular biometric values correlate positively.

Comparison of three rebound tonometers in normal and glaucomatous dogs

OBJECTIVE

The objectives of the study were to compare intraocular pressure (IOP) readings across a wide range and obtained via three rebound tonometers in ADAMTS10-mutant Beagle-derived dogs with different stages of open-angle glaucoma (OAG) and normal control dogs and to investigate the effect of central corneal thickness (CCT).

ANIMALS STUDIED

Measurements were performed on 99 eyes from 50 Beagle-derived dogs with variable genetics-16 non-glaucomatous and 34 with ADAMTS10-OAG. Seventeen OAG eyes were measured twice-with and without the use of IOP-lowering medications.

PROCEDURES

IOP was measured in each eye using three tonometers with their "dog" setting-ICare® Tonovet (TV), ICare® Tonovet Plus® (TVP), and the novel Reichert® Tono-Vera® Vet (TVA)-in randomized order. CCT was measured with the Accutome® PachPen. Statistical analyses included one-way ANOVA, Tukey pairwise comparisons, and regression analyses of tonometer readings and pairwise IOP-CCT Pearson correlations (MiniTab®).

RESULTS

A total of 116 IOP measurements were taken with each of the three tonometers. When comparing readings over a range of ~7-77 mmHg, mean IOPs from the TV were significantly lower compared with TVP (-4.6 mmHg, p < .001) and TVA (-3.7 mmHg, p = .001). We found no significant differences between TVA and TVP measurements (p = .695). There was a moderate positive correlation between CCT and IOP for TVA (r = 0.53, p < .001), TVP (r = 0.48, p < .001), and TV (r = 0.47, p < .001).

CONCLUSIONS

Our data demonstrate strong agreement between TVP and TVA, suggesting that the TVA may similarly reflect true IOP values in canines. CCT influenced IOP measurements of all three tonometers.

Effect of anesthetic induction with propofol, alfaxalone or ketamine on intraocular pressure in cats: a randomized masked clinical investigation

OBJECTIVE

To compare the effect of propofol, alfaxalone and ketamine on intraocular pressure (IOP) in cats.

STUDY DESIGN

Prospective, masked, randomized clinical trial.

ANIMALS

A total of 43 ophthalmologically normal cats scheduled to undergo general anesthesia for various procedures.

METHODS

Following baseline IOP measurements using applanation tonometry, anesthesia was induced with propofol (n = 15), alfaxalone (n = 14) or ketamine (n = 14) administered intravenously to effect. Then, midazolam (0.3 mg kg^-1) was administered intravenously and endotracheal intubation was performed without application of topical anesthesia. The IOP was measured following each intervention. Data was analyzed using one-way anova and repeated-measures mixed design with post hoc analysis. A p-value <0.05 was considered significant.

RESULTS

Mean ± standard error IOP at baseline was not different among groups (propofol, 18 ± 0.6; alfaxalone, 18 ± 0.7; ketamine, 17 ± 0.5 mmHg). Following induction of anesthesia, IOP increased significantly compared with baseline in the propofol (20 ± 0.7 mmHg), but not in the alfaxalone (19 ± 0.8 mmHg) or ketamine (16 ± 0.7 mmHg) groups. Midazolam administration resulted in significant decrease from the previous measurement in the alfaxalone group (16 ± 0.7 mmHg), but not in the propofol group (19 ± 0.7 mmHg) or the ketamine (16 ± 0.8 mmHg) group. A further decrease was measured after intubation in the alfaxalone group (15 ± 0.9 mmHg).

CONCLUSIONS AND CLINICAL RELEVANCE

Propofol should be used with caution in cats predisposed to perforation or glaucoma, as any increase in IOP should be avoided.

Increased Risk of Ocular Hypertension in Patients With Cushing's Disease

PRCIS

An increased risk of ocular hypertension was seen in Cushing's disease.

INTRODUCTION

Systemic steroid use is a significant risk factor for increased intraocular pressure (IOP). The incidence of ocular hypertension may rise to 30%-40% of the general population due to topical or systemic glucocorticoid usage. However, the incidence of ocular hypertension in endogenous hypercortisolemia, as well as the ophthalmological outcomes after endocrine remission due to surgical resection, remain unknown.

MATERIALS AND METHODS

The IOP, visual field, and peripapillary retinal nerve fiber layer thickness were documented in all patients with Cushing's disease (CD) admitted to a tertiary pituitary center for surgery from January to July 2019. Patients with acromegaly and patients with nonfunctioning pituitary adenoma (NFPA) during the same study period served as controls. We calculated the odds ratio (OR), identified the risk factors of developing ocular hypertension, and presented postoperative trends of the IOP.

RESULTS

A total of 52 patients (38.4±12.4 y old) with CD were included. The IOP was higher in patients with CD (left 19.4±5.4 mm Hg and right 20.0±7.1 mm Hg) than in patients with acromegaly (left 17.5±2.3 mm Hg and right 18.6±7.0 mm Hg, P =0.033) and patients with NFPA (left 17.8±2.6 mm Hg and right 17.4±2.4 mm Hg, P =0.005). A total of 21 eyes (20.2%) in patients with CD were diagnosed with ocular hypertension compared with 4 eyes (4.7%) in the acromegaly group and 4 eyes (4.5%) in the NFPA group. The OR of developing ocular hypertension in patients with CD was 5.1 [95% confidence interval (CI), 1.3-25.1, P =0.029] and 6.6 (95% CI, 1.8-30.3, P =0.007) when compared with the 2 control groups. Among patients with CD, those with a higher urine-free cortisol were more likely to develop ocular hypertension (OR=19.4, 95% CI, 1.7-72.6). The IOP decreased at 1 month after surgery in patients with CD, and the change was sustained for 3 months after surgery.

CONCLUSIONS

An increased risk of ocular hypertension was seen in CD and suggests that endogenous hypercortisolemia should be considered as part of the glaucoma assessment. This result warrants the discretion of both ophthalmologists and neuroendocrinologists.

[Diagnostics, clinical aspects and genetics of congenital corneal opacities]

BACKGROUND

Congenital corneal opacities are comparatively rare diseases with high amblyogenic potential.

PURPOSE

The present work provides an overview of the diagnostics, clinical aspects and genetics of congenital corneal opacities.

METHODS

A literature search was carried out to compile an overview and illustration with own clinical case examples.

RESULTS

Differentiated diagnostics are of high importance in the treatment of patients with congenital corneal opacities. A close cooperation between the medical departments involved and also the parents is absolutely essential. The structured classification of congenital corneal opacities provides the basis for a targeted treatment.

DISCUSSION

The causes and the clinical symptoms of congenital corneal opacities are manifold. The correct diagnosis should be made early and in an interdisciplinary manner. Based on this, conservative and surgical treatment measures can be planned and an impending development of amblyopia can be specifically counteracted.

Aniridic glaucoma: An update

Aniridia is a congenital bilateral ocular disorder with dominant autosomal inheritance. More than 50% of patients will develop aniridic glaucoma (AG) during their lives. Open angle glaucoma is more common in aniridia, but a closed angle mechanism has been described in relation with anterior rotation of the rudimentary iris, occluding trabecular meshwork. Diagnosis and follow-up of AG is difficult in relation with the presence of keratopathy, nystagmus and foveal hypoplasia. Central corneal thickness usually measures more than 600 microns, which prevents achieving a reliable value of intraocular pressure. Medical treatment of AG is no different from the rest of glaucoma. It is recommended to use preservative free formulations, and combined therapy is often required. Surgical treatment is needed in many cases. There is no consensus on the first line surgery for AG, but in open angle AG, angle surgery is usually first choice, and glaucoma drainage devices are the next preferred surgical technique. In closed angle AG glaucoma drainage devices are usually the first choice, with trabeculectomy as the second preferred surgical technique.

Goniotomy for initial and re-surgery for childhood glaucoma in Northern India

Purpose

The aim of this study was to describe the effectiveness of goniotomy for childhood glaucoma in Indian eyes.

Methods

Consecutive patients with pediatric glaucoma who underwent goniotomy between July 2017 and June 2020, in a single center in Northwest India were prospectively analyzed. Goniotomy was done as a primary procedure or a re-do surgery of the untreated angle in failed filtering surgery. Success was defined as intraocular pressure (IOP) ≦18 mm Hg with or without 2 topical medications.

Results

A total of 172 eyes of 126 children underwent goniotomy during this period (37.9% of all pediatric glaucoma surgeries). Goniotomy comprised 132 of 211 (62.5%) primary pediatric glaucoma surgeries and 40 of 243 (16.5%) re-do surgeries. 145, 112, and 54 eyes had a six months, 1-year and 2-year follow-up, respectively. At 1 year, success rates in Primary Congenital Glaucoma (PCG) were 79.7% for primary surgery and 68.4% for re-do surgery. For non-PCG eyes, the success rate was 62% at 1 year. Among PCG subgroups, infantile and newborn glaucoma had 87.5% and 57.1% success rates, respectively. On logistic regression analysis, lower baseline IOP and lesser axial length at presentation were significantly predictive of successful outcomes (P = 0.03 and P = 0.02, respectively). At 1 year, in the primary surgery group, 50% had good vision (better than logMAR 0.5), 28.9% had moderate (better than LOGMAR 1.0) and 20% had severe visual impairment. There were no significant intraoperative or post-operative complications.

Conclusion

Goniotomy appears to be an effective surgery for childhood glaucoma in Indian eyes. Being minimally invasive, it obviates the need for conjunctival and scleral dissection and antifibrotic agents.

Comparative Evaluation of Rebound and Perkins Tonometers in Pediatric Glaucoma With Varied Corneal Characteristics

PRECIS

Icare tonometer overestimated intraocular pressure (IOP) as compared with Perkins and this variation was higher in IOP>19 mm Hg and corneal opacity in patients with pediatric glaucoma.

PURPOSE

To compare the IOP measured by Icare ic200 with Perkins tonometer in pediatric glaucoma with different corneal characteristics.

METHODS

Patients of pediatric glaucoma posted for routine examination under anesthesia, age below 12 years were enrolled. All patients underwent IOP measurement with Perkins and Icare ic200 tonometer by the same observer. Basic demographic data and other relevant clinical data were recorded. Central corneal thickness (CCT), horizontal corneal diameter, and corneal characteristics such as cornea clarity was recorded.

RESULTS

A total of 194 eyes of 105 patients were analyzed. The difference between Perkins and Icare IOP was -0.816 mm Hg with the Bland-Altman plot 95% limits of agreement (LoA) from -11.194 to 9.562 mm Hg and 5.1% (10) values lying outside LoA. At IOP <19 mm Hg, the difference was -0.65 mm Hg and IOP ≥19 mm Hg, the difference was higher, -1.12 mm Hg. In the clear cornea group (123 eyes), the difference in IOP by 2 tonometers was -0.776 mm Hg with the Bland-Altman plot 95% LoA between -10.679 and 9.128 mm Hg. In hazy corneas (36 eyes), the difference in IOP was 0.531 mm Hg. The Bland-Altman plot showed 95% LoA between -6.242 and 7.303 mm Hg. In the scarred cornea group (35 eyes), the difference in IOP between the 2 was -2.343 mm Hg and the Bland-Altman plot showed wide 95% LoA from -16.302 to 11.616 mm Hg.

CONCLUSION

Icare tonometer overestimated IOP as compared with Perkins and this variation was higher in eyes with IOP≥19 mm Hg, CCT >615 μm, and scarred corneas. A moderate correlation between IOP and CCT for both tonometers was noted.

Aniridic glaucoma: An update

Aniridia is a congenital bilateral ocular disorder with dominant autosomal inheritance. More than 50% of patients will develop aniridic glaucoma (AG) during their lives. Open angle glaucoma is more common in aniridia, but a closed angle mechanism has been described in relation with anterior rotation of the rudimentary iris, occluding trabecular meshwork. Diagnosis and follow-up of AG is difficult in relation with the presence of keratopathy, nystagmus and foveal hypoplasia. Central corneal thickness usually measures more than 600 microns, which prevents achieving a reliable value of intraocular pressure. Medical treatment of AG is not different from the rest of glaucoma. It is recommended to use preservative free formulations, and combined therapy is often required. Surgical treatment is needed in many cases. There is no consensus on the first line surgery for AG, but in open angle AG, angle surgery is usually first choice, and glaucoma drainage devices are the next preferred surgical technique. In closed angle AG glaucoma drainage devices are usually the first choice, with trabeculectomy as the second preferred surgical technique.

The Use of Oral Midazolam to Facilitate the Ophthalmic Examination of Children with Autism and Developmental Disorders

Ophthalmic examinations of developmentally delayed/autistic children are challenging. Oral midazolam may be a viable alternative to general anaesthesia for this indication. Single-centre retrospective cohort study (January 2018-March 2020). Oral midazolam (0.5 mg/kg, max 15 mg). Metrics included: patient demographics, examination completion rate, duration of stay and adverse events. 50 oral midazolam examinations were performed (45 patients). Mean age was 79.12 months. All had developmental delay (66.67% autism). Time to ophthalmic examination was 60.31 minutes. Eye examination was successfully completed in 98%. No adverse events were reported. Mean stay was 3.35 hours. Oral midazolam (0.5 mg/kg, max 15 mg) is associated with safe, successful completion of ophthalmic examinations in children previously unexaminable in clinic.

Impact of corneal parameters on intraocular pressure measurements in different tonometry methods

AIM

To evaluate the impact of central corneal thickness (CCT) and corneal curvature on intraocular pressure (IOP) measurements performed by three different tonometers.

METHODS

IOP in 132 healthy eyes of 66 participants was measured using three different tonometry techniques: Goldmann applanation tonometer (GAT), Pascal dynamic contour tonometer (DCT), and ICare rebound tonometer (RT). CCT and corneal curvature were assessed.

RESULTS

In healthy eyes, DCT presents significantly higher values of IOP than GAT (17.34±3.69 and 15.27±4.06 mm Hg, P<0.0001). RT measurements are significantly lower than GAT (13.56±4.33 mm Hg, P<0.0001). Compared with GAT, DCT presented on average 2.51 mm Hg higher values in eyes with CCT<600 µm and 0.99 mm Hg higher results in eyes with CCT≥600 µm. The RT results were lower on average by 1.61 and 1.95 mm Hg than those obtained by GAT, respectively. Positive correlations between CCT in eyes with CCT<600 µm were detected for all IOP measurement techniques, whereas a similar relationship was not observed in eyes with thicker corneas. A correlation between IOP values and keratometry in the group with CCT<600 µm was not detected with any of the tonometry methods. In thicker corneas, a positive correlation was found for GAT and mean keratometry values (R=0.369, P=0.005).

CONCLUSION

The same method should always be chosen for routine IOP control, and measurements obtained by different methods cannot be compared. All analysed tonometry methods are dependent on CCT; thus, CCT should be taken into consideration for both diagnostics and monitoring.

[360° trabeculotomy for pediatric glaucoma]

Congenital glaucoma disease leads to blindness if left untreated. It is estimated that 1 child in 10,000 in Germany is born with congenital glaucoma. In adults the disease develops slowly and insidiously, whereas congenital glaucoma leads to a rapid growth of the eye (buphthalmos) mostly directly after birth due to a very high intraocular pressure. The cause is dysgenesis of the iridocorneal angle. Successful operative treatment of congenital glaucoma is possible in the majority of cases (approximately 80-90%). The treatment of childhood glaucoma is primarily surgical. Since 1960 classical probe trabeculotomy has been the most commonly used procedure, which has the advantage that unlike goniotomy, it can also be performed in cases with clouding of the cornea. In this surgery the canal of Schlemm is probed and the inner wall as well as the trabecular meshwork is opened inwardly over approximately 120°. In recent years the 360° trabeculotomy procedure has become established, in which an illuminated catheter filled with viscoelastic material is used (as with conventional canaloplasty) to dilate the canal of Schlemm. The trabecular meshwork is then inwardly opened by pulling on the ends of the catheter. The results of this method are explained in this article.