Scanning laser polarimetry in glaucoma

Chemical Insights into Topical Agents in Intraocular Pressure Management: From Glaucoma Etiopathology to Therapeutic Approaches

Glaucoma encompasses a group of optic neuropathies characterized by complex and often elusive etiopathology, involvihttng neurodegeneration of the optic nerve in conjunction with abnormal intraocular pressure (IOP). Currently, there is no cure for glaucoma, and treatment strategies primarily aim to halt disease progression by managing IOP. This review delves into the etiopathology, diagnostic methods, and treatment approaches for glaucoma, with a special focus on IOP management. We discuss a range of active pharmaceutical ingredients used in glaucoma therapy, emphasizing their chemical structure, pharmacological action, therapeutic effectiveness, and safety/tolerability profiles. Notably, most of these therapeutic agents are administered as topical formulations, a critical aspect considering patient compliance and drug delivery efficiency. The classes of glaucoma therapeutics covered in this review include prostaglandin analogs, beta blockers, alpha agonists, carbonic anhydrase inhibitors, Rho kinase inhibitors, and miotic (cholinergic) agents. This comprehensive overview highlights the importance of topical administration in glaucoma treatment, offering insights into the current state and future directions of pharmacological management in glaucoma.

Single pixel polarimetric imaging through scattering media

Polarimetric imaging can provide valuable information about biological samples in a wide range of applications. Detrimental tissue scattering and depolarization however currently hamper in vivo polarization imaging. In this work, single pixel imaging is investigated as a means of reconstructing polarimetric images through scattering media. A theoretical imaging model is presented, and the recovery of the spatially resolved Mueller matrix of a test object behind a scattering phantom is demonstrated experimentally.

Predictive Factors for Visual Field Conversion: Comparison of Scanning Laser Polarimetry and Optical Coherence Tomography

PURPOSE

The purpose of this study was to compare the ability of scanning laser polarimetry (SLP) and spectral-domain optical coherence tomography (SD-OCT) to predict future visual field conversion of subjects with ocular hypertension and early glaucoma.

METHODS

All patients were recruited from the Erlangen glaucoma registry and examined using standard automated perimetry, 24-hour intraocular pressure profile, and optic disc photography. Peripapillary retinal nerve fiber layer thickness (RNFL) measurements were obtained by SLP (GDx-VCC) and SD-OCT (Spectralis OCT). Positive and negative predictive values (PPV, NPV) were calculated for morphologic parameters of SLP and SD-OCT. Kaplan-Meier survival curves were plotted and log-rank tests were performed to compare the survival distributions. Contingency tables and Venn-diagrams were calculated to compare the predictive ability.

RESULTS

The study included 207 patients-75 with ocular hypertension, 85 with early glaucoma, and 47 controls. Median follow-up was 4.5 years. A total of 29 patients (14.0%) developed visual field conversion during follow-up. SLP temporal-inferior RNFL [0.667; 95% confidence interval (CI), 0.281-0.935] and SD-OCT temporal-inferior RNFL (0.571; 95% CI, 0.317-0.802) achieved the highest PPV; nerve fiber indicator (0.923; 95% CI, 0.876-0.957) and SD-OCT mean (0.898; 95% CI, 0.847-0.937) achieved the highest NPV of all investigated parameters. The Kaplan-Meier curves confirmed significantly higher survival for subjects within normal limits of measurements of both devices (P<0.001). Venn diagrams tested with McNemar test statistics showed no significant difference for PPV (P=0.219) or NPV (P=0.678).

CONCLUSIONS

Both GDx-VCC and SD-OCT demonstrate comparable results in predicting future visual field conversion if taking typical scans for GDx-VCC. In addition, the likelihood ratios suggest that GDx-VCC's nerve fiber indicator<30 may be the most useful parameter to confirm future nonconversion. (http://www.ClinicalTrials.gov number, NTC00494923; Erlangen Glaucoma Registry).

Ocular and Systemic Risk Factors and Correlation with Glaucomatous Damage in Normal Tension Glaucoma

Background

Normal tension glaucoma (NTG) is a clinical entity that poses a diagnostic and therapeutic challenge. The study elaborates ocular and systemic risk factors of NTG in the South Indian population. It determines the correlation between risk factors and severity of glaucomatous damage.

Methods

This descriptive study was done on 81 eyes of 41 patients. A brief history of hypertension, heart disease, migraine, and family history of glaucoma were noted. The parameters measured include blood pressure, lipid profile, visual acuity, refraction, intraocular pressure (IOP) by applanation tonometry, diurnal variation, slit lamp biomicroscopy, central corneal thickness (CCT), and perimetry (Humphrey 24-2).

Results

The mean age was 51.75 years. There was female predilection (63.41%). Thirteen patients (32.5%) had hypertension, five (12.5%) had migraine, and seven had hyperlipidemia (17.5%). Perfusion pressure demonstrated a negative correlation value of -0.319 (rho value) with visual field defects (p<0.05) and -0.266 (rho value) with glaucomatous cupping (p=0.093). The IOP varied from 10 mmHg to 19 mmHg with a mean of 15.34. The average CCT was 522.06±36.09 microns. Neuroretinal rim thinning was seen in 12 eyes (14.8%), polar notching in six eyes (7.4%), and peripapillary atrophy in 20 eyes (24.6%). Two eyes (2.4%) had splinter hemorrhage at disc margin. A lower value of CCT was associated with lower IOP, a weak positive correlation (r value 0.121). Optic disc cupping is strongly associated with severity of field defects, r value 0.743, (p<0.00).

Conclusion

Normal tension glaucoma is common in females. Hypertension and lower diastolic perfusion pressure are important risk factors. Lower CCT is associated with lower IOP (applanation tonometry). Optic disc cupping and diastolic perfusion pressure strongly correlate with severity of visual field defects.