The Relationship Between Quantitative Pupillometry and Estimated Ganglion Cell Counts in Patients With Glaucoma

Asymmetric Intraocular Pressure Changes in Dominant and Contralateral Eyes: The Dark Room Prone Provocative Test

PURPOSE

To evaluate changes in intraocular pressure (IOP) in dominant and contralateral eyes following the dark room prone provocative test (DRPPT) in the study subjects with shallow anterior chamber.

METHODS

This was a prospective, single-center, non-randomized controlled trial of 43 subjects (86 eyes) with shallow anterior chamber. The dominant eye was identified using the card-hole method. The study subjects underwent the DRPPT for one hour. Pre- and post-DRPPT IOP was measured using an I-Care tonometer, and pupillary parameters, including amplitude of constriction, peak constriction velocity, and peak re-dilation velocity, were also measured using the RAPDx® dynamic pupillometer.

RESULTS

Significant increases in IOP were observed in both the dominant and contralateral eyes after DRPPT, compared to their respective pre-DRPPT IOP levels. (p < .01). Moreover, IOP variation before and after DRPPT was significantly greater in the dominant eye than in the contralateral eye (median 3.60 mmHg vs. 2.70 mmHg, p < .05). The dominant eyes exhibited a smaller amplitude of constriction (1.07 ± 0.35 mm vs 1.14 ± 0.34 mm, P < .05) and slower constriction velocity (3.71 ± 1.12 mm/s vs 3.78 ± 1.11 mm/s, P < .05) as compared to the contralateral eyes.

CONCLUSIONS

This study demonstrated that the dominant eye exhibited greater IOP changes after DRPPT than the contralateral eye. Additionally, it showed smaller pupil constriction and slower contraction, indicating a higher likelihood of pupil blockage in the dominant eye with shallow anterior chambers. This asymmetry partially explains the monocular onset of acute angle-closure attacks.

Quantitative automated pupillometry in diabetic patients and correlation with retinal nerve fibre layer thickness

OBJECTIVE

To evaluate pupillary function in diabetic patients by automated pupillometry, and to study the correlation between retinal nerve fibre layer (RNFL) thickness and pupillary parameters.

METHODS

Diabetic patients underwent detailed systemic and ophthalmic examination including automated pupillometry. The pupillometer used a white stimulus and was equipped with a high-resolution infrared (880 nm) camera. Static pupillary diameters were captured at different levels of background intensity-photopic high (100 cd/m2), photopic low (10 cd/m2), mesopic high (1 cd/m2), and mesopic low (0.1 cd/m2). Dynamic pupillary responses were elicited with white-light flashes (total luminance 100 cd/m2, stimulus on time 200 ms, off time 3300 ms). RNFL thickness was measured using spectral domain optical coherence tomography (OCT) RESULTS: The study had 38 diabetic patients with retinopathy (DWR), 27 diabetic patients without retinopathy (DWOR), and 25 healthy controls. Static pupillometry showed significant differences between the three groups. Diabetic patients, both with and without retinopathy had significantly smaller pupillary diameters compared to controls, (p < 0.001). The amplitude of contraction and velocity of contraction was significantly lower in diabetic patients compared to controls (p < 0.001), and between DWR compared to DWOR (p < 0.001). Percent pupillary contraction differed between DWR and controls (p = 0.001) There was a significant difference in superior RNFL thickness between DWR and DWOR (p = 0.032). The superior quadrant RNFL correlated with the maximum number of pupillometry parameters.

CONCLUSION

The amplitude and velocity of contraction are affected early in diabetic autonomic dysfunction. There is a relationship between RNFL thickness and pupillometry parameters in diabetic patients, indicating simultaneous neurodegeneration and autonomic neuropathy.

Comparison of an AI-based mobile pupillometry system and NPi-200 for pupillary light reflex and correlation with glaucoma-related markers

Introduction

Glaucoma is a leading cause of blindness, often progressing asymptomatically until significant vision loss occurs. Early detection is crucial for preventing irreversible damage. The pupillary light reflex (PLR) has proven useful in glaucoma diagnosis, and mobile technologies like the AI-based smartphone pupillometer (AI Pupillometer) offer a promising solution for accessible screening. This study assesses the reliability of the AI Pupillometer in detecting glaucoma.

Methods

In Experiment 1, 20 healthy participants were assessed using both the AI Pupillometer and the NPi-200 device to evaluate equivalence in measuring PLR. Each eye underwent three trials. Experiment 2 included 46 participants, 24 with primary open-angle glaucoma (POAG) and 22 healthy controls. PLR measurements from the AI Pupillometer were correlated with structural and functional ocular parameters. An additional study expanded the sample to 387 participants (103 glaucoma patients, 284 controls), focusing on differential pupillometry parameters to minimize ambient light interference.

Results

In Experiment 1, the AI Pupillometer demonstrated strong correlations with the NPi-200 in key parameters like initial pupil size (r = 0.700), constricted pupil size (r = 0.755), and constriction velocity (r = 0.541), confirming its reliability. In Experiment 2, although no statistically significant differences in light-corrected PLR parameters were found between groups, glaucoma patients had a marginally higher constricted pupil size (p = 0.1632). Significant correlations were observed between pupillometry and advanced ocular imaging results, notably between constriction amplitude and visual field loss. The additional study revealed significant differences in constriction amplitude (p = 0.014) and relative pupil size change (p = 0.0072) between glaucoma patients and controls, reinforcing the AI Pupillometer's diagnostic potential.

Conclusion

This study confirms the AI Pupillometer as a reliable, accessible tool for glaucoma screening. Mobile diagnostics could enhance early detection, improving outcomes for glaucoma patients.

Quantitative Pupillometry: Clinical Applications for the Internist

From the time of Galen, examination of the pupillary light reflex has been a standard of care across the continuum of health care. The growing body of evidence overwhelmingly supports the use of quantitative pupillometry over subjective examination with flashlight or penlight. At current time, pupillometers have become standard of care in many hospitals across 6 continents. This review paper provides an overview and rationale for pupillometer use and highlights literature supporting pupillometer-derived measures of the pupillary light reflex in both neurological and non-neurological patients across the health care continuum.

Basics, benefits, and pitfalls of pupillometers assessing visual function

Numerous commercially and non-commercially available pupillometers are nowadays able to assess various biological functions in humans, by evaluating pupils' dynamics in response to specific stimuli. However, the use of pupillometers for ophthalmic afferent evaluations (i.e., photoreceptoral responses) in real-world settings is relatively limited. Recent scientific and technological advances, coupled with artificial intelligence methods have improved the performance of such devices to objectively detect, quantify, and classify functional disturbances of the retina and the optic nerve. This review aims to summarize the scientific principles, indications, outcomes, and current limitations of pupillometry used for evaluation of afferent pathways in ophthalmic clinical settings.

Pupillary response to chromatic light stimuli as a possible biomarker at the early stage of glaucoma: a review

Glaucoma is a multifactorial neurodegenerative disease of the optic nerve currently considered a severe health problem because of its high prevalence, being the primary cause of irreversible blindness worldwide. The most common type corresponds to Primary Open-Angle Glaucoma. Glaucoma produces, among other alterations, a progressive loss of retinal ganglion cells (RGC) and its axons which are the key contributors to generate action potentials that reach the visual cortex to create the visual image. Glaucoma is characterized by Visual Field loss whose main feature is to be painless and therefore makes early detection difficult, causing a late diagnosis and a delayed treatment indication that slows down its progression. Intrinsically photosensitive retinal ganglion cells, which represent a subgroup of RGCs are characterized by their response to short-wave light stimulation close to 480 nm, their non-visual function, and their role in the generation of the pupillary reflex. Currently, the sensitivity of clinical examinations correlates to RGC damage; however, the need for an early damage biomarker is still relevant. It is an urgent task to create new diagnostic approaches to detect an early stage of glaucoma in a prompt, quick, and economical manner. We summarize the pathology of glaucoma and its current clinical detection methods, and we suggest evaluating the pupillary response to chromatic light as a potential biomarker of disease, due to its diagnostic benefit and its cost-effectiveness in clinical practice in order to reduce irreversible damage caused by glaucoma.

Effect of low-dose atropine eyedrops on pupil metrics: results after half a year of treatment and cessation

Purpose

To evaluate the effect of low-dose atropine eyedrops on pupil metrics.

Methods

This study was based on a randomized, double-masked, placebo-controlled, and cross-over trial in mainland China. In phase 1, subjects received 0.01% atropine or placebo once nightly. After 1 year, the atropine group switched to placebo (atropine-placebo group), and the placebo group switched to atropine (placebo-atropine group). Ocular parameters were measured at the crossover time point (at the 12th month) and the 18th month.

Results

Of 105 subjects who completed the study, 48 and 57 children were allocated into the atropine-placebo and placebo-atropine groups, respectively. After cessation, the photopic pupil diameter (PD) and mesopic PD both decreased (− 0.46 ± 0.47 mm, P < 0.001; − 0.30 ± 0.74 mm, P = 0.008), and the constriction ratio (CR, %) increased (4.39 ± 7.54, P < 0.001) compared with values at the crossover time point of the atropine-placebo group; pupil metrics of the atropine-placebo group had no difference from the values at the crossover time point of the placebo-atropine group. After 6 months of treatment, the photopic PD and the mesopic PD increased (0.54 ± 0.67 mm, P < 0.001; 0.53 ± 0.89 mm, P < 0.001), the CR (%) decreased (− 2.53 ± 8.64, P < 0.001) compared with values at the crossover time point of the placebo-atropine group. There was no significant relationship between pupil metrics and myopia progression during 0.01% atropine treatment.

Conclusion

Pupil metrics and the CR could return to pre-atropine levels after cessation. Pupil metrics had no significant effect on myopia progression during treatment.

Artificial intelligence and deep learning in glaucoma: Current state and future prospects

Over the past few years, there has been an unprecedented and tremendous excitement for artificial intelligence (AI) research in the field of Ophthalmology; this has naturally been translated to glaucoma-a progressive optic neuropathy characterized by retinal ganglion cell axon loss and associated visual field defects. In this review, we aim to discuss how AI may have a unique opportunity to tackle the many challenges faced in the glaucoma clinic. This is because glaucoma remains poorly understood with difficulties in providing early diagnosis and prognosis accurately and in a timely fashion. In the short term, AI could also become a game changer by paving the way for the first cost-effective glaucoma screening campaigns. While there are undeniable technical and clinical challenges ahead, and more so than for other ophthalmic disorders whereby AI is already booming, we strongly believe that glaucoma specialists should embrace AI as a companion to their practice. Finally, this review will also remind ourselves that glaucoma is a complex group of disorders with a multitude of physiological manifestations that cannot yet be observed clinically. AI in glaucoma is here to stay, but it will not be the only tool to solve glaucoma.

Comparisons of ganglion cell-inner plexiform layer loss patterns and its diagnostic performance between normal tension glaucoma and primary open angle glaucoma: a detailed, severity-based study

AIM

To evaluate the patterns of macular ganglion cell-inner plexiform layer (GCIPL) loss in normal tension glaucoma (NTG) and primary open angle glaucoma (POAG) in a detailed, disease severity-matched way; and to assess the diagnostic capabilities of GCIPL thickness parameters in discriminating NTG or POAG from normal subjects.

METHODS

A total of 157 eyes of 157 subjects, including 57 normal eyes, 51 eyes with POAG and 49 eyes with NTG were enrolled and strictly matched in age, refraction, and disease severity between POAG and NTG groups. The average, minimum, superotemporal, superior, superonasal, inferonasal, inferior, and inferotemporal GCIPL thickness, and the average, superior, temporal, inferior, and nasal retinal nerve fiber layer (RNFL) thickness were obtained by Cirrus optical coherence tomography (OCT). The diagnostic capabilities of OCT parameters were assessed by area under receiver operating characteristic (AUROC) curves.

RESULTS

Among all the OCT thickness parameters, no statistical significant difference between NTG group and POAG group was found (all P>0.05). In discriminating NTG or POAG from normal subjects, the average and inferior RNFL thickness, and the minimum GCIPL thickness had better diagnostic capabilities. There was no significant difference in AUROC curve between the best GCIPL thickness parameter (minimum GCIPL) and the best RNFL thickness parameter in discriminating NTG (inferior RNFL; P=0.076) and indiscriminating POAG (average RNFL; P=0.913) from normal eyes.

CONCLUSION

Localized GCIPL loss, especially in the inferior and inferotemporal sectors, is more common in NTG than in POAG. Among all the GCIPL thickness parameters, the minimum GCIPL thickness has the best diagnostic performance in differentiating NTG or POAG from normal subjects, which is comparable to that of the average and inferior RNFL thickness.