Inconsistency of the Published Definition of Ocular Hypertension

Associations of statin use with the onset and progression of open-angle glaucoma: A systematic review and meta-analysis

Background

Statins, the first-line therapy for hyperlipidemia, have received considerable attention as candidates for glaucoma treatments given its neuroprotective effects. In this systematic review and meta-analysis, we intended to assess the association of statin use with the onset and progression of open-angle glaucoma (OAG).

Methods

Databases including PubMed, Embase and Web of Science Core Collection were searched for longitudinal studies reporting the association between statin use and OAG onset or progression on Feb 3, 2021. A meta-analysis was performed for the association between statin use and OAG onset. Relative risks (RRs) with 95% confidential intervals (CIs) were retrieved from included studies and pooled using random-effects models. Potential risks of bias were evaluated by the Newcastle-Ottawa Quality Assessment Scale for all eligible studies. This study had been registered on PROSPERO (CRD 42021232172).

Findings

515,788 participants (mean age 68.7 years, 62.3% female) from ten studies were included in the systematic review of the association between statin use and OAG onset, and 26,347 OAG patients (mean age 67.3 years, 52.2% female) from seven studies were included for the association between statin use and OAG progression. Potential risks of bias were detected in 12 studies, which were mainly attributed to selection and confounding bias. In addition, 515,600 participants from eight studies were included in the meta-analysis which collectively showed that statin use was associated with a reduced risk of OAG onset (Pooled RR: 0.95; 95%CI: 0.93-0.98; I2=0.199;). No significant heterogeneity or publication bias was found for studies included in the meta-analysis. There were inconsistent evidences for the association between statin use and OAG progression.

Interpretation

Statin use is associated with a slightly lower risk of OAG onset based on existing evidences from longitudinal observational studies, the association between statin use and OAG progression remains inconclusive. The included evidences were typically weak due to poor study design and under-powered studies. Current findings should be interpreted cautiously and still need to be validated in further research.

Funding

The National Key R&D Program of China (2018YFC0116500), Science and Technology Planning Project of Guangdong Province (2013B20400003), the China Postdoctoral Science Foundation (2019TQ0365), the National Natural Science Foundation of China (82000901 and 82101171).

Elevated intraocular pressure increases melatonin levels in the aqueous humour

PURPOSE

To study the levels of melatonin in the aqueous humour of normotensive and hypertensive intraocular pressure (IOP) patients and to compare them to an animal model of glaucoma.

METHODS

A total of 37 eyes of 37 patients who underwent cataract surgery were included in the study and were divided into normotensive patients, with IOP below 21 mmHg (n = 23), and hypertensive patients, with IOP > 21 mmHg (n = 14). Glaucomatous DBA/2J (n = 6) and control C57BL/6J (n = 6) mice presenting 3 and 12 months of age for each strain were also used. Human and mice aqueous humours were aspirated using a 30-gauge Rycroft cannula on a tuberculin syringe and further processed to quantify melatonin by high-performance liquid chromatography analysis.

RESULTS

Melatonin levels in normotensive patients (IOP below 21 mmHg) presented values as medians (first quartile; third quartile) of 14.62 (5.38;37.99) ng/ml (n = 23), while hypertensive patients (IOP above 21 mmHg) showed melatonin concentrations of 46.63 (10.28; 167.28) ng/ml (n = 14; p < 0.039). Glaucoma mice presented melatonin values of 0.37 (0.34; 0.59) ng/ml (at 3 months of age, before the pathology starts), which increased to 1.55 (0.94; 1.88) ng/ml (at 12 months of age, when the pathology is fully developed and IOP is maximum; n = 6, p < 0.001). Control mice did not significantly modified melatonin concentrations between 3 and 12 months of age.

CONCLUSION

Patients with high IOP present increased concentrations of melatonin in their aqueous humour compared to normotensive patients. This has been confirmed in a glaucomatous animal model in which it has been possible to see a correlation between the development of the pathology, with an increase in IOP, and a concomitant elevation of melatonin in the aqueous humour.

Evaluation of retinal nerve fiber layer thickness profile in thyroid ophthalmopathy without optic nerve dysfunction

AIM

To evaluate retinal nerve fiber layer (RNFL) thickness profile in patients of thyroid ophthalmopathy with no clinical signs of optic nerve dysfunction.

METHODS

A prospective, case-control, observational study conducted at a tertiary care centre. Inclusion criteria consisted of patients with eyelid retraction in association with any one of: biochemical thyroid dysfunction, exophthalmos, or extraocular muscle involvement; or thyroid dysfunction in association with either exophthalmos or extra-ocular muscle involvement; or a clinical activity score (CAS)>3/7. Two measurements of RNFL thickness were done for each eye, by Cirrus HD-optical coherence tomography 6mo apart.

RESULTS

Mean age of the sample was 38.75y (range 13-70y) with 18 males and 22 females. Average RNFL thickness at first visit was 92.06±12.44 µm, significantly lower than control group (101.28±6.64 µm) (P=0.0001). Thickness of inferior quadrant decreased from 118.2±21.27 µm to 115.0±22.27 µm after 6mo (P=0.02). There was no correlation between the change in CAS and RNFL thickness.

CONCLUSION

Decreased RNFL thickness is an important feature of thyroid orbitopathy, which is an inherent outcome of compressive optic neuropathy of any etiology. Subclinical RNFL damage continues in the absence of clinical activity of the disease. RNFL evaluation is essential in Grave's disease and active intervention may be warranted in the presence of significant damage.

Higher incidence of steroid-induced ocular hypertension in keratoconus

BACKGROUND

To compare intraocular pressure (IOP) changes following topical dexamethasone administration for 1 month in keratoconic versus normal eyes.

METHODS

This is a retrospective, single-center, non-randomized case series evaluation of 350 eyes. Two groups were formed: normal/control Group A (nA =73), eyes that underwent excimer laser photorefractive keratectomy; and keratoconic (KCN) Group B (nB =277), eyes that were subjected to partial laser photorefractive keratectomy combined with collagen cross-linking (The Athens Protocol). All eyes received the same post-operative regimen of topical dexamethasone 0.1 % for at least 1 month. Goldmann applanation tonometry IOP readings and central corneal thickness (CCT) measurements were monitored. Cases with induced ocular hypertension (OHT, defined as post-operative IOP higher than 21 mmHg), were identified and correlated to refractive procedure, gender, and corneal thickness.

RESULTS

At 4 weeks postoperatively, OHT was noted on 27.4 % (20 /73 eyes) in Group A, and 43.7 % (121 /277 eyes) in KCN Group B, (p <0.01). Six months post-operatively (following 5-months of discontinuing topical dexamethasone treatment and commencing treatment of IOP-lowering medications), OHT rate was 1.8 % in Group A and 3.9 % in the KCN Group B.

CONCLUSION

This study demonstrates a potentially significant pre-disposition of keratoconic eyes to the development of steroid-induced OHT.

Diagnostic accuracy of the iCare rebound tonometer compared to the Perkins applanation tonometer in assessing intraocular pressure in rural patients

Background: Vision health is recognized as a critical unmet need in North America. The ocular morbidity associated with glaucoma results from increased intraocular pressure (IOP) and early detection is crucial for the management of glaucoma. Our objective was to find a diagnostically accurate screening tool for intraocular hypertension that can be used in rural communities. We sought to validate the diagnostic accuracy of the iCare rebound tonometer against the gold standard Perkins applanation tonometer (PAT) in measuring IOP.

Methods: Patients from two rural communities in Ontario, Canada visiting their optometrists for routine appointments had their IOP measured by a non-contact tonometer (NCT), an iCare rebound tonometer, and a Perkins applanation tonometer (PAT). Values of sensitivity, specificity, and likelihood ratios for a positive and negative result were calculated for the iCare and the NCT.

Results: Complete data was collected from 209 patients. Overall, the iCare tonometer had high levels of validity, as compared to the gold standard PAT. The iCare tonometer displayed excellent sensitivity of 98.3% (90–99%, 95% CI) and excellent negative likelihood ratio of 0.024 (0.0088–0.066, 95% CI) which is useful for ruling out intraocular hypertension.

Conclusions: The iCare tonometer is a reasonably valid tool for detecting elevated IOP. Its ease of use, simplicity, and accessibility makes it a good screening tool to improve eye health in rural areas.

Descemet stripping with automated endothelial keratoplasty: A comparative study of outcome in patients with preexisting glaucoma

PURPOSE

To compare postoperative complications after Descemet stripping with automated endothelial keratoplasty (DSAEK) in patients with and without glaucoma.

METHODS

For this retrospective study a series of 298 DSAEK cases performed at the Doheny Eye Institute were taken, we compared postoperative complications in eyes with glaucoma on medication (55) or with previous glaucoma surgeries (64) with a time-matched group of all other DSAEK cases (179, control).

RESULTS

With a mean follow-up of 1.85 ± 1.12 years, the complication rates were 12.8%, 11.1%, and 26.8% for postoperative graft detachment, graft failure, and IOP elevation, respectively. Graft detachment was an independent risk factor for graft failure (odds ratio OR = 12.35, 95% confidence interval CI [5.46-27.90], P < 0.001). Graft detachment was not associated with either history of glaucoma or glaucoma surgery (P > 0.05). Glaucoma on medication had no increased risks of graft failure compared to normal eyes (P = 0.38). However, increased risk of failure was seen in eyes with prior incisional glaucoma surgeries (OR = 4.26, 95% CI [1.87-9.71], P < 0.001). Medically managed glaucoma has increased risks of postoperative IOP elevation (OR = 2.39, 95% CI [1.25-4.57], P = 0.013), whereas surgically managed glaucoma has no significant elevation (P = 0.23). Elevation of IOP was not significantly correlated with graft failure (P = 0.21).

CONCLUSION

DSAEK is the preferred treatment for corneal endothelial dystrophy. We observed that having glaucoma or glaucoma surgery is not associated with graft detachment. A history of glaucoma surgery and postoperative graft detachment appeared to be important risk factors for graft failure. And more studies are indicated to study long-term IOP evolution in post-DSAEK patients and its association with graft survival.

The effect of ketamine on intraocular pressure in pediatric patients during procedural sedation

OBJECTIVES

Ketamine is one of the most commonly used procedural sedation and analgesia (PSA) agents in pediatric emergency departments (PEDs). It is considered a very safe and reliable agent, with limited respiratory suppression, hemodynamic effects, and adverse outcomes. However, physicians are often reluctant to use ketamine for patients with eye injuries due to a concern that ketamine might increase intraocular pressure (IOP). The objective was to measure IOP in previously healthy children receiving ketamine for PSA for a reason other than eye injury.

METHODS

This was a prospective noninferiority study of patients seen in an academic tertiary care children's hospital emergency department (ED) who required ketamine for PSA. The authors measured IOP in the right eye as soon as possible after ketamine had been administered and then at 2.5, 5, and 10 minutes after ketamine had been administered.

RESULTS

Eighty patients were enrolled (28 between 1 and 5 years of age, 26 between 6 and 10 years, 26 between 11 and 15 years); 49 (61%) were male. Procedures requiring PSA included fracture/dislocation reduction (63%), abscess incision and drainage (16%), laceration repair (11%), dental abscess incision and drainage (6%), and other (4%). The mean total ketamine dosage was 1.6 mg/kg (95% confidence interval [CI] = 1.4 to 1.7). The mean initial IOP was 17.5 mm Hg (95% CI = 16.4 to 18.6 mm Hg) and at 2.5 minutes was 18.9 mm Hg (95% CI = 17.9 to 19.9 mm Hg). The mean difference was 1.4 mm Hg (95% CI = 0.4 to 2.4 mm Hg). Using a noninferiority margin of 2.6 mm Hg (15%), noninferiority (no significant elevation in IOP) was demonstrated with 95% confidence between the first and second readings.

CONCLUSIONS

 Ketamine does not significantly increase IOP in pediatric patients without eye injuries receiving typical PSA dosages in the PED. Further study should assess its safety in patients with ocular injury.

Ketamine sedation is not associated with clinically meaningful elevation of intraocular pressure

BACKGROUND

Ketamine is widely used for procedural sedation, but there is limited knowledge on whether ketamine use is associated with elevated intraocular pressure (IOP).

OBJECTIVE

The aim of this study was to examine whether there are clinically important elevations of IOP associated with ketamine use during pediatric procedural sedation.

METHODS

We prospectively enrolled children without ocular abnormalities undergoing procedural sedation that included ketamine for nonperiorbital injuries. We measured IOP for each eye before and at 1, 3, 5, 15, and 30 minutes after initial intravenous ketamine administration. We performed Bland-Altman plots to determine if IOP measurements in both eyes were in agreement. Linear regression was used to model the mean IOP of both eyes as a function of time, dose, and age, with a robust sandwich estimator to account for repeated measures.

RESULTS

Among 25 participants, median (interquartile range) age was 11 (9-12) years, and 18 (72%) were male. Median ketamine dose was 1.88 mg/kg (interquartile range, 1.43-2.03 mg/kg; range 0.96-4 mg/kg). Bland-Altman plots demonstrated a mean difference of IOP between eyes near zero at all time points. The largest predicted difference from baseline IOP occurred at 15 minutes, with an estimated change of 1.09 mm Hg (95% confidence interval, -0.37 to 2.55). The association between ketamine dose and mean IOP was not statistically significant or clinically meaningful (P = .90; estimated slope, 0.119 [95% confidence interval, -1.71 to 1.95]). There were no clinically meaningful levels of increased measured average IOP reached at any time point.

CONCLUSIONS

At dosages of 4 mg/kg or less, there are not clinically meaningful associations of ketamine with elevation of IOP.

The value of tests in the diagnosis and management of glaucoma

PURPOSE

To assess the noneconomic value of tests used in the diagnosis and management of glaucoma, and explore the contexts and factors that determine such value.

DESIGN

Perspective.

METHODS

Selected articles from primary and secondary sources were reviewed and interpreted in the context of the authors' clinical and research experience, influenced by our perspectives on the tasks of reducing the global problem of irreversible blindness caused by glaucoma. The value of any test used in glaucoma is addressed by 3 questions regarding: its contexts, its kind of value, and its implicit or explicit benefits.

RESULTS

Tonometry, slit-lamp gonioscopy, and optic disc evaluation remain the foundation of clinic-based case finding, whether in areas of more or less abundant resources. In resource-poor areas, there is urgency in identifying patients at risk for severe functional loss of vision; screening strategies have proven ineffective, and efforts are hindered by the inadequate allocation of support. In resource-abundant areas, the wider spectrum of glaucoma is addressed, with emphasis on early detection of structural changes of little functional consequence; these are increasingly the focus of new and expensive technologies whose clinical value has not been established in longitudinal and population-based studies. These contrasting realities in part reflect differences among the value ascribed, often implicitly, to the tests used in glaucoma.

CONCLUSIONS

The value of any test is determined by 3 aspects: its context of usage; its comparative worth and to whom its benefit accrues; and how we define historically what we are testing. These multiple factors should be considered in the elaboration of priorities for the development and application of tests in glaucoma.

Primary open-angle glaucoma: clinical update

Glaucoma is an optic neuropathy that is usually associated with an elevated intraocular pressure. Primary open-angle glaucoma (POAG) is the most common type of glaucoma and is progressive and bilateral but typically asymmetric in patients. Studies have shown that reducing intraocular pressure reduces the risk of vision loss. In the United States, medical intervention by means of prescription eye drops is the initial line of treatment. Nurses play an important role in educating individuals, particularly older adults, about the importance of routine eye care to earlier diagnose, treat, and adequately manage eye diseases such as POAG.

Heritability of intraocular pressure in older female twins

PURPOSE

To examine the heritability of intraocular pressure (IOP) among older women not diagnosed as having glaucoma.

DESIGN

Cross-sectional twin study.

PARTICIPANTS

94 monozygotic (MZ) and 96 dizygotic (DZ) female twin pairs aged 63-76 years and not diagnosed as having glaucoma.

METHODS

Intraocular pressure was measured using a noncontact tonometer. The contributions of genetic and environmental factors to individual differences in IOP were estimated by applying an independent pathway model to twin data.

MAIN OUTCOME MEASURES

Contribution of genetic and environmental effects to the variation in IOP among MZ and DZ twins.

RESULTS

Mean IOP of the study population was 14.1 mmHg (+/- standard deviation 3.1) with no differences observed neither between the MZ and the DZ individuals, nor between the left and the right eyes. The pair-wise correlations for IOP of the right eye were .61 in MZ and .25 in DZ and for the left eye .63 and .42. The phenotypic correlation between the left and the right eye IOP was high (r = 0.81), suggesting that they were indices of a single trait. Quantitative genetic modeling revealed that for both eyes 64% (95% confidence interval [CI], 53-71) of the variance in IOP was explained by additive genetic effects and 18% (95% CI, 11-27) by nonshared environmental factors in common. In addition, 18% (95% CI, 15-23) of the variance in IOP was explained by nonshared environmental factors specific to each eye.

CONCLUSIONS

Additive genetic influences explained most of the individual differences in IOP among older women not diagnosed as having glaucoma. Because elevated IOP is an important risk factor for glaucoma, genetic factors underlying IOP may have a significant role in determining the risk for glaucoma, a complex progressive disease leading to death of ganglion cells.