A pharmacologic pupillary test in the diagnosis of diabetic autonomic neuropathy

The evaluation of pupil diameter by using Sirius before and after phacoemulsification in healthy, diabetic and hypertension patients

BACKGROUND

Pupil size can affect the selection of the ablation region in refractive surgery and intraocular lens design in cataract surgery. Therefore, the evaluation of pupil diameter (PD), one of the anterior segment parameters, is an important component of ophthalmological examination.

MATERIAL AND METHODS

Seventy-one healthy patients, 64 patients with Systemic Hypertension (HT), and 65 patients with Diabetes Mellitus (DM) scheduled for phacoemulsification were included in the study. PD was measured before and one month after surgery using combined Scheimpflug-Placido disk topography (Sirius, CSO Inc.). Preoperative PD values of the groups were compared. The PD of the groups was compared in the 1st month after surgery. Then, preoperative and postoperative pupil diameter values of the groups were compared. The effect of the surgery on the change in pupil diameter (effect value) in the groups was also examined.

RESULTS

Pre- and postoperative PD only differed significantly between the healthy and DM groups (P = .039 and P = .045, respectively). PD decreased in all three groups after phacoemulsification. Pre-and postoperative PD differed significantly in the healthy group (4.78 ± 0.94 and 3.01 ± 0.48 mm, respectively, P < .05). Pre- and postoperative PD values also differed significantly (4.69 ± 0.84 and 2.95 ± 0.42 mm, respectively, P < .05). In the DM group, Pre- and postoperative PD also differed significantly in the DM group (4.38 ± 1.08 and 2.82 ± 0.43 mm, respectively, P < .05). The effect values of PD changes differed in the healthy, DM, and HT groups (1.95, 1.41, and 2.28, respectively). Phacoemulsification was observed to have a greater effect on PD change in HT patients.

CONCLUSIONS

PD was smaller in DM patients than in the other groups. PD decreased in all three groups after phacoemulsification. This change should be remembered when planning cataract surgery for chronic metabolic patients.

Palpebral Fissure Response to Phenylephrine Indicates Autonomic Dysfunction in Patients With Type 1 Diabetes and Polyneuropathy

Purpose

The superior and inferior tarsal muscles are sympathetically innervated smooth muscles. Long-term diabetes often leads to microvascular complications, such as, retinopathy and autonomic neuropathy. We hypothesized that diabetes induces (1) sympathetic paresis in the superior and inferior tarsal muscles and that this measure is associated with (2) the severity of diabetic retinopathy, (3) the duration of diabetes, and (4) autonomic function. In addition, association between the severity of retinopathy and autonomic function was investigated.

Methods

Forty-eight participants with long-term type 1 diabetes and confirmed distal symmetrical polyneuropathy were included. Palpebral fissure heights were measured bilaterally in response to topically applied 10% phenylephrine to the right eye. The presence of proliferative diabetic retinopathy (PDR) or nonproliferative diabetic retinopathy and disease duration were denoted. Time and frequency derived heart rate variability parameters obtained from 24-hour continuous electrocardiography were recorded.

Results

The difference in palpebral fissure heights between phenylephrine treated and untreated eyes (∆PFH) was 1.02 mm ± 0.29 (P = 0.001). The ∆PFH was significantly lower in the PDR group (0.41 mm ± 0.43 vs. 1.27 mm ± 1.0), F(1,35) = 5.26, P = 0.011. The ∆PFH was lower with increasing diabetes duration, r(37) = -0.612, P = 0.000. Further, the ∆PFH was lower with diminished autonomic function assessed as total frequency power in electrocardiogram (r = 0.417, P = 0.014), and sympathetic measures of very low (r = 0.437, P = 0.010) and low frequency power (r = 0.384, P = 0.025).

Conclusions

The ∆PFH is a simple ambulatory sympathetic measure, which was associated with the presence of PDR, disease duration, and autonomic function. Consequently, ∆PFH could potentially be an inexpensive and sensitive clinical indicator of autonomic dysfunction.

The Relationship of the Urotensin-2 Level in the Aqueous Humor with Systemic Diseases and Pupil Size: Comparative Study

Purpose: To detect the presence of urotensin-2 (U-II) in the aqueous humor and evaluate the relationship between aqueous humor level and systemic diseases and pupil size. Methods: The study included 88 patients who underwent cataract surgery. Those with a pupil diameter (PD) of up to 4 mm were considered to have small dilation, those with 4-7 mm of dilatation were considered to have moderate dilation, and those with a PD of more than 7 mm considered to have large dilation. Patients with HT (hypertension) were classified as group 1, those with DM (diabetes mellitus) as group 2, and those with HT+DM as group 3, and those without any systemic disease as group 4. The U-II levels in humor aqueous samples taken from anterior chamber were measured. Results: When compared with the control group, it was observed that the level of U-II in the aqueous humor of the HT, DM, and DM+HT groups was significantly higher (P < 0.05). At the same time, when we compared the DM+HT group with the other groups, the level of U-II in the aqueous humor was significantly higher compared to the group with DM (P < 0.05). The U-II levels of the aqueous humor were higher in the patients with small pupils compared to the remaining groups (P < 0.005). Conclusion: U-II may play a role in small pupil pathophysiology. In addition, it was determined that patients with HT and/or diabetes had higher U-II levels in the aqueous humor than healthy individuals.

[The state of ocular neurosensory apparatus in diabetes mellitus]

Diabetes mellitus is one of the most common chronic diseases in the world. Among its late complications that can lead to disability is diabetic neuropathy (DN). Patients diagnosed with DN often also have diabetic retinopathy (DR). According to available data, DR prevalence ranges from 30 to 60%. For a long time, DR has been considered a microvascular disease. However, more data has been emerging recently that indicates the presence of other components in the pathophysiology of DR. Neurodegenerative changes in the retina can be detected in patients with diabetes mellitus before clinical signs of diabetic retinopathy appear. Accumulation of extracellular glutamate, oxidative stress, reduction of neuroprotective factors synthesized by the retina are all believed to lead to neuronal apoptosis and glial cell dysfunction. This cascade of reactions subsequently causes disruption of the hematoretinal barrier and damage to neurovascular apparatus of the retina. This results in the defeat of capillaries of the retinal vascular system, which is consistently characterized by the loss of pericytes and the formation of unperfusable capillaries. The concept of neurodegeneration being an early component of DR provides an opportunity to explore alternative therapies to prevent the onset of vision loss in diabetes mellitus.

Phacoemulsification without preoperative mydriasis in patients with age-related cataract associated with type 2 diabetes

Aim

To study the effect of intracameral injection of preservative-free lignocaine to induce pupil dilatation, without using any preoperative dilating eyedrops or intraoperative mydriatics in patients with age-related cataract associated with type 2 diabetes mellitus.

Design

This was a prospective, observational, and interventional case series conducted at a tertiary eyecare center in rural India.

Materials and methods

A total of 32 patients underwent phacoemulsification under topical anesthesia for visually significant cataract. Preoperative pupillary diameter was measured 3 days prior to surgical procedure under mydriatics (tropicamide 0.8%, phenylephrine hydrochloride 5%). Intraoperative pupillary dilatation was achieved by 1% intracameral lignocaine solution alone. Effective phacoemulsification time (EPT), total surgical time, and final pupillary diameter were recorded at the conclusion of surgery.

Results

The average duration of diabetes was 11.2 (range 5–25) years. There was no difference in dilatation by preoperative pupil-dilating drops (5.2±0.5 mm, range 3–8.3 mm) and intracameral 1% lignocaine during the surgical procedure (P=0.63). There was a negative correlation (r=−0.92) between diabetes duration and dilatation of pupils with dilating drops and intracameral lignocaine. The duration of the surgery, EPT, and phacoemulsification chop had statistically insignificant effects on mydriasis, while the grade of the nucleus had a statistically significant effect on mydriasis. Intracameral lignocaine had no significant effect on blood pressure or pulse. There were no surgical complications that could have compromised the visual outcome. None of the patients developed macular edema in a follow-up period of 3 months; 28 patients (87.5%) had best-corrected visual acuity from 20/30 to 20/20.

Conclusion

Intracameral lignocaine 1% provides sufficient mydriasis for the safe phacoemulsification of cataract in patients with type 2 diabetes of variable duration.

Predictive Value of Pupillary Response to Mydriatic Agents for Diagnosis of Retinopathy of Prematurity

Purpose:

To evaluate the feasibility of screening for retinopathy of prematurity (ROP) by assessing the pupillary response to mydriatics.

Methods:

This observational case series included 134 eyes of 67 premature infants with birth weight less than 2,000 grams and gestational age less than 33 weeks. A composite eye drop composed of phenylephrine 1%, tetracaine and tropicamide 0.5% was applied 3 times within 5-minute intervals and pupil diameters were measured. The eyes were examined by experienced ROP specialists using an indirect ophthalmoscope. Zone and stage of ROP, presence of plus disease and need for treatment were recorded. The relationship between the pupillary response to mydriatics, and presence and severity of ROP was evaluated. Logistic regression was used for statistical analysis.

Results:

According to receiver operating characteristic (ROC) curve analysis, final pupil diameter after mydriatic administration was found the most accurate factor among other factors to recognize ROP zone I from zones II and III (Area under ROC: 0.92 [95%CI: 0.85-0.98]). The best cutoff value for final pupil diameter was 5.6 mm, because it could differentiate involvement of zone I from zones II and III with sensitivity of 80% and specificity of 100%.

Conclusion:

Response of the pupil to mydriatic eye drops may be useful as a less invasive method for rough estimation of ROP in high risk babies who need emergent attention; however, it cannot be considered as a screening test due to its low sensitivity.

Studying the effect of iris mechanics on the pupillary light reflex using brimonidine-induced anisocoria

PURPOSE

To study and correct for the limiting effect of iris mechanics on the amplitude of light-evoked pupil contractions in order to derive a more clinically accurate assessment of afferent input to the visual system.

METHODS

Transient pupil responses were recorded to a series of 1-second red Ganzfeld light stimuli with a stepwise increase in stimulus intensity using a binocular infrared computerized pupillometer. One eye of eight healthy subjects was treated with 0.2% brimonidine tartrate ophthalmic solution to induce pupil size reduction. The amount of pupil contraction as a function of stimulus intensity was compared between the brimonidine-treated, miotic eye and the untreated eye.

RESULTS

BRIMONIDINE TREATMENT PRODUCED SIGNIFICANT REDUCTION IN PUPIL SIZE IN HEALTHY SUBJECTS (MEAN REDUCTION IN PUPIL SIZE: 1.78 ± 0.35 mm, P < 0.05). For increasing light intensity, the treated pupil started to show reduced pupil contractions compared with the contralateral untreated pupil when the peak of pupil contraction reached an average pupil size of 3.25 ± 0.61 mm (range, 2.38-4.44 mm). When measured by percent pupil contraction (contraction amplitude/baseline pupil diameter), the pupil response as a function of stimulus intensity in the treated, miotic eye did not differ from that in the untreated eye.

CONCLUSIONS

Iris mechanics limits the amount of pupil contraction and can act to reduce the assessed neuronal integration of the pupil light reflex. Pupil response assessed by using percent contraction amplitude is least affected by mechanical effects and provides a more accurate approximation of afferent input.