Intraocular pressures after ketamine and sevoflurane in children with glaucoma undergoing examination under anaesthesia

[Tonometry: Review and Perspectives]

Reliable and repeated IOP measurement are essential in the diagnosis and treatment of glaucoma. In this second part, the other contact tonometry and non-contact tonometry are presented. The clinical value of the different methods and the value of multimodality in tonometry will be discussed based on a review of the literature, and the latest innovations with telemetric IOP sensors will be introduced.

Tonometrie: Rückblick und Ausblick (Teil 2)

In 2. Teil des Beitrags werden die sonstigen Kontakttonometer und die Nonkontakttonometrie präsentiert. Es wird anhand einer Revue der Literatur über den klinischen Wert der verschiedenen Methoden und den Wert der Multimodalität in der Tonometrie diskutiert; ferner werden die letzten Innovationen mit den telemetrischen IOD-Sensoren eingeführt.

Exome Sequencing Reveals SLC4A11 Variant Underlying Congenital Hereditary Endothelial Dystrophy (CHED2) Misdiagnosed as Congenital Glaucoma

Autosomal recessive congenital hereditary endothelial dystrophy (CHED2) may be misdiagnosed as primary congenital glaucoma (PCG) due to similar clinical phenotypes during early infancy. In this study, we identified a family with CHED2, which was previously misdiagnosed as having PCG, and followed up for 9 years. Linkage analysis was first completed in eight PCG-affected families, followed by whole-exome sequencing (WES) in family PKGM3. The following in silico tools were used to predict the pathogenic effects of identified variants: I-Mutant 2.0, SIFT, Polyphen-2, PROVEAN, mutation taster and PhD-SNP. After detecting an SLC4A11 variant in one family, detailed ophthalmic examinations were performed again to confirm the diagnosis. Six out of eight families had CYP1B1 gene variants responsible for PCG. However, in family PKGM3, no variants in the known PCG genes were identified. WES identified a homozygous missense variant c.2024A>C, p.(Glu675Ala) in SLC4A11. Based on the WES findings, the affected individuals underwent detailed ophthalmic examinations and were re-diagnosed with CHED2 leading to secondary glaucoma. Our results expand the genetic spectrum of CHED2. This is the first report from Pakistan of a Glu675Ala variant with CHED2 leading to secondary glaucoma. The p.Glu675Ala variant is likely a founder mutation in the Pakistani population. Our findings suggest that genome-wide neonatal screening is worthwhile to avoid the misdiagnosis of phenotypically similar diseases such as CHED2 and PCG.

A review of current ophthalmic anaesthetic practice

INTRO

Ophthalmic surgery ranks among the commonest procedures performed worldwide. This review considers the range of anaesthetic techniques available to the modern ophthalmic anaesthetist, and practical considerations to evaluate in different circumstances. There is a brief summary of the main issues pertaining to the common ophthalmic subspecialties and operations.

SOURCES OF DATA

Pubmed.

AREAS OF AGREEMENT

We present a view of contemporary ophthalmic anaesthetic practice as we see it, both from current UK clinical experience, and the available published evidence.

AREAS OF CONTROVERSY

There is an ongoing debate about the safety of sharp needle blocks (SNBs) compared to subtenons and topical techniques, but SNBs still have a role to play, both in specific cases, and in circumstances where resources are limited.

GROWING POINTS

It remains a challenge to provide safe, cost effective anaesthesia to a growing patient base with ever increasing demands and medical comorbidities. There is a continuing trend towards replacing general with local anaesthesia where possible.

RESEARCH

Research in ophthalmic anaesthesia, as in so many areas, has been plagued by heterogeneity and small studies. A coordinated, large scale, multicentred approach to research questions in future would help to guide best practice with more certainty.

Effect of general anaesthesia on intraocular pressure in paediatric patients: a systematic review

OBJECTIVES

Assessment of the impact of general anaesthetic agents on intraocular pressure (IOP) in children via systematic review.

METHODS

Pubmed, Embase, and CENTRAL databases were systematically searched to identify randomised controlled trials, prospective, and interventional studies. The search included all studies through October 5, 2018 with no date or language restrictions. A linear mixed-effects regression analysis was performed to study the change in IOP after general anaesthesia (GA).

RESULTS

The strategy identified 518 studies that met search criteria. Six studies (531 eyes) were included for quantitative synthesis. Seven categories of mixed and non-mixed induction and maintenance agents were compared. When assessing all agents utilising a model of mean IOP as a function of time, IOP decreased after induction phase at a rate of -0.59 ± 0.19 mmHg/min (P value = 0.006).

CONCLUSIONS

This systematic review showed that most anaesthetic agents significantly decrease IOP over time after the induction phase of general anaesthesia in children. An understanding of the effects of GA on IOP is critical for those performing paediatric ophthalmic examinations under anaesthesia.

How does sevoflurane induction, followed by a ketamine maintenance infusion, affect intraocular pressure? Establishment of an anaesthetic protocol for paediatric glaucoma examinations under anaesthesia

Accurate measurement of intraocular pressure (IOP) is essential in paediatric glaucoma management. Children require serial measurements and examination under anaesthesia (EUA). Most anaesthetic agents reduce IOP, and the ideal time to measure IOP under anaesthesia is questionable.

STUDY PURPOSE

To determine the effect of sevoflurane induction, followed by intravenous ketamine infusion on IOP, in children undergoing EUA for glaucoma or suspected glaucoma, and to establish the earliest time point at which reliable, repeatable IOP measurements can be obtained under anaesthesia.

METHOD

A prospective, descriptive study of IOP changes occurring in children requiring EUAs. A standardised anaesthetic protocol: sevoflurane induction, intravenous cannulation, 2 mg/kg intravenous ketamine bolus and 4 mg/kg/hour maintenance for 15 min. IOP measurements (taken supine with a Perkins applanation tonometer) and physiological variables were recorded.

RESULTS

IOPs were measured in 25 children (50 eyes). Twenty-six eyes (52%) were glaucomatous. Mean patient age was 29 months (2-88 months). Physiological variables returned to baseline at 8 min, correlating with recorded sevoflurane elimination. Mean IOP after sevoflurane induction was 3.68 mm Hg lower than with ketamine maintenance at 15 min (95% CI 1.35 to 6.02 mm Hg) (p=0.002). Contrastingly, the difference in IOP between ketamine anaesthesia at 15 min and near wakefulness was 0.28 mm Hg (95% CI -2.23 to 2.79 mm Hg) (p=0.826).

CONCLUSION

Sevoflurane's IOP-lowering effect is reversed 15 min after the discontinuation of the inhalational gas, if anaesthesia is maintained with an intravenous ketamine infusion. IOP measurements appear to stabilise at this time point until the point of near wakefulness and may reflect awake values.

Résultats pressionnels et visuels à long terme de la sclérectomie profonde dans le glaucome congénital primitif

OBJECTIVE

To estimate long term future of pressure and vision of children who underwent DS for CPG.

MATERIAL AND METHODS

Children affected by CPG, aged from 1 day to 3 years at the time of the diagnosis were retrospectively included between 1999 and 2014. All benefited from a DS with use of antimetabolites. Preoperative and long-term post-operative intraocular pressures (IOP), per and postoperative complications as well as visual acuity and refractive status were estimated. Complete IOP control was defined by a postoperative IOP ≤16 mmHg without medical treatment.

RESULTS

141 eyes of 71 children were included (sex ratio: 1.02). Mean follow-up was 56.6 ±9.6 months. Final average IOP among the whole sample was 11.3 +/-7 mmHg. The rate of total success was 69.4 %, partial success 27.6 % and 3 % failure at the last check. No complications were seen in 85.1 % of cases (n=120 eyes). Among 37 children analyzed for visual acuity, maintained visual acuity was found in 50 % of cases (n= 37 eyes).

CONCLUSION

DS allows obtaining good IOP control with a very low rate of complications, and should be considered as a technique of choice in the surgical management of CPG. This study is of particular relevance because it has been led on a long term period and on an important staff considering the rare prevalence of the condition.

Review on the Management of Primary Congenital Glaucoma

Despite being documented in medical history from over 2400 years ago, primary congenital glaucoma (PCG), being a disease with low incidence rate, remains a challenge to ophthalmologists. The article provides a broad overview on the pathophysiology and diagnostic approach to PCG with major emphasis on the treatment options of PCG. While reviewing on the well-established treatment options, namely goniotomy, trabeculo-tomy and combined trabeculotomy-trabeculectomy, emphasis has also been made to recent updates on secondary treatments: trabeculectomy, antimetabolites, glaucoma-drainage devices and cyclodestructive procedures. It is, however, important to note that the rarity of PCG places limitations on study design, most studies are, thus, retrospective, nonrandomized and have different definitions of surgical success. Ophthalmologists need to interpret the results with critical thinking and formulate individual treatment plans for each patient. How to cite this article: Yu Chan JY, Choy BNK, Alex LK Ng, Shum JWH. Review on the Management of Primary Congenital Glaucoma. J Curr Glaucoma Pract 2015;9(3):92-99.

[Epidemiology and clinical characteristics of primary congenital glaucoma]

INTRODUCTION

Primary congenital glaucoma (PCG) is a rare and sight threatening condition. Few large epidemiological studies are available in the literature concerning this condition. The purpose of the study was to evaluate the epidemiological and clinical characteristics of children affected by PCG.

PATIENTS AND METHOD

Children affected by PCG, from 1 day to 3 years old at the time of diagnosis were retrospectively included between 1999 and 2014. The analysis concerned the pregnancy, family history, initial referral, clinical presentation with description of the classic findings in this condition, mean age at first consultation, duration of follow-up and presence of a delay in treatment, defined as a delay of over one month from the appearance of clinical signs until diagnosis. Two groups were defined according to age at appearance of the clinical signs: "early" group prior to 2 months old and "late" group beyond 2 months up until 3 years old.

RESULTS

One hundred and forty-one eyes of 71 children were included, with 49.3% girls (n=35 children) and 50.7% boys (n=36 children) for a male:female ratio of 1.02. The "early" group included 50 children i.e. 70.3% of the population; the "late" group 21 children or 29.7% of the population. A first-degree family history of congenital glaucoma existed in 28% of cases (n=19). The average age at first consultation was 13.1 months for the entire population, and the mean duration of follow-up was 56.6 months. Involvement was bilateral in 99.3% of cases (n=70 children) and the most frequent clinical sign was buphthalmos in 64.5% of eyes (n=91 eyes). Treatment was delayed in 35.3% of cases (n=25 children).

DISCUSSION AND CONCLUSION

This study is of particular relevance because it was performed over a long period and on a large population, considering the rare prevalence of the pathology, and has found epidemiological and clinical data comparable with those available in the literature for similar populations.

TGF-β2-mediated ocular hypertension is attenuated in SPARC-null mice

PURPOSE

Transforming growth factor-β2 (TGF-β2) has been implicated in the pathogenesis of primary open-angle glaucoma through extracellular matrix (ECM) alteration among various mechanisms. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein that regulates ECM within the trabecular meshwork (TM), and is highly upregulated by TGF-β2. We hypothesized that, in vivo, SPARC is a critical regulatory node in TGF-β2-mediated ocular hypertension.

METHODS

Empty (Ad.empty) or TGF-β2-containing adenovirus (Ad.TGF-β2) was injected intravitreally into C57BL6-SV129 WT and SPARC-null mice. An initial study was performed to identify a stable period for IOP measurement under isoflurane. The IOP was measured before injection and every other day for two weeks using rebound tonometry. Additional mice were euthanized at peak IOP for immunohistochemistry.

RESULTS

The IOP was stable under isoflurane during minutes 5 to 8. The IOP was significantly elevated in Ad.TGF-β2-injected (n = 8) versus Ad.empty-injected WT (n = 8) mice and contralateral uninjected eyes during days 4 to 11 (P < 0.03). The IOPs were not significantly elevated in Ad.TGF-β2-injected versus Ad.empty-injected SPARC-null mice. However, on day 8, the IOP of Ad.TGF-β2-injected SPARC-null eyes was elevated compared to that of contralateral uninjected eyes (P = 0.0385). Immunohistochemistry demonstrated that TGF-β2 stimulated increases in collagen IV, fibronectin, plasminogen activator inhibitor-1 (PAI-1), connective tissue growth factor (CTGF), and SPARC in WT mice, but only PAI-1 and CTGF in SPARC-null mice (P < 0.05).

CONCLUSIONS

SPARC is essential to the regulation of TGF-β2-mediated ocular hypertension. Deletion of SPARC significantly attenuates the effects of TGF-β2 by restricting collagen IV and fibronectin expression. These data provide further evidence that SPARC may have an important role in IOP regulation and possibly glaucoma pathogenesis.

Respiratory complications associated with ketamine anesthesia for ophthalmic procedures following intraocular pressure measurement in children

BACKGROUND

We compared respiratory complications (RCs) in children who received intramuscular (IM) versus intravenous (IV) or no ketamine for intraocular pressure (IOP) measurement to test our observation that IM ketamine is associated with higher incidence of RCs.

MATERIALS AND METHODS

We analyzed 149 eye examinations under anesthesia with ketamine in 27 patients and 263 non-ketamine examinations under anesthesia in 81 patients using a mixed effects logistic regression model.

RESULTS

IM KETAMINE WAS STRONGLY ASSOCIATED WITH INCREASED ODDS OF RCS COMPARED TO NO KETAMINE (ODDS RATIO (OR): 20.23, P < 0.0001) and to IV ketamine (OR: 6.78, P = 0.02), as were higher American Society of Anesthesiologists (ASA) classification (OR: 2.60, P = 0.04), and the use of volatile agents (OR: 3.32, P = 0.02).

CONCLUSION

Further studies should be conducted to confirm our observation of increased RCs with IM ketamine.

Conditions that can be mistaken as early childhood glaucoma

Primary congenital glaucoma (isolated goniodysgenesis) has classic phenotypic features such as increased measured intraocular pressure, globe enlargement (buphthalmos) with associated myopia, Descemet membrane tears, corneal haze/scarring with associated astigmatism, iris atrophy, and optic nerve cupping. These signs also occur in developmental glaucoma (anterior segment dysgeneses) with infantile onset. However, similar findings can occur in other pediatric conditions which are sometimes are mistaken as early childhood glaucoma.