Role of anterior segment optical coherence tomography angiography in the assessment of acute chemical ocular injury: a pilot animal model study.

To examine the use of anterior segment-optical coherence tomography angiography (AS-OCTA) in the assessment of limbal ischemia in an animal model chemical ocular injury. We conducted a prospective study using an established chemical ocular injury model in 6 rabbits (12 eyes), dividing the cornea limbus into 4 quadrants. Chemical injury grade was induced based on extent of limbal injury (0 to 360 degrees) and all eyes underwent serial slit-lamp with AS-OCTA imaging up to one month. Main outcome measure was changes in AS-OCTA vessel density (VD) comparing injured and control cornea limbal quadrants within 24 h and at one month. AS-OCTA was able to detect differences in limbal VD reduction comparing injured (3.3 ± 2.4%) and control quadrants (7.6 ± 2.3%; p < 0.001) within 24 h of ocular chemical injury. We also observed that AS-OCTA VD reduction was highly correlated with the number of quadrants injured (r = - 0.89; p < 0.001; 95% CI - 5.65 to - 1.87). Corneal vascularization was detected by AS-OCTA in injured compared to control quadrants (10.1 ± 4.3% vs 7.0 ± 1.2%; p = 0.025) at 1 month. Our animal pilot study suggests that AS-OCTA was able to detect limbal vessel disruption from various severities of acute chemical insult, and in the future, could potentially serve as an adjunct in providing objective grading of acute ocular chemical injury once validated in a clinical trial.

Anterior segment ischemia: etiology, assessment, and management.

Anterior segment ischemia (ASI) is a potentially serious but rare complication of strabismus surgery. Among several risk factors, ASI occurs after strabismus surgery because of the nature of the anterior segment circulation. Disinsertion of rectus muscles leads to a decrease in the blood supply to the various anterior segment structures. We report a series of retrospective and prospective studies performed by our group focused on determining the risk of anterior segment ischemia following strabismus surgery, diagnosis, and modifications to surgical techniques to minimize the impact on anterior segment circulation. We found a significant decrease in postoperative anterior segment blood flow when operating vertical rectus muscles. Plication procedures preserve anterior segment circulation, and modifications to the technique allow the performance of adjustable sutures. Small adjustable selective procedures that spare the ciliary vessels have been demonstrated to be effective in patients with vertical and torsional diplopia. Ciliary sparing augmented adjustable transposition surgery decreases the risk of anterior segment ischemia while allowing management of potential post-operative alignment complications. Finally, ocular coherence tomography angiography is a valuable quantitative and qualitative technique to evaluate anterior segment ischemia. Strabismus surgeons should be aware of the risks of anterior segment ischemia when operating vertical rectus muscles. Modifications to standard surgical techniques allow surgeons to perform complex strabismus surgery in patients at risk for anterior segment ischemia.

[Application fluorescein angiography: a new method for assessment of anterior eye segment hemomicrocirculation].

PURPOSE: To develop a noninvasive fluorescein angiography (FAG) method for the anterior eye segment (AES) assessment which would imply using the most-ordered site of bulbar conjunctival capillary bed as the object of dye administration. MATERIAL AND METHODS: The study enrolled 30 individuals (41 eyes) with no evident ocular pathology and significant systemic diseases aged from 18 to 70 years and 19 patients with uveitis, of whom 10 patients (10 eyes) aged 43-57 had anterior uveitis and 9 patients (10 eyes) aged 17-29 had pars planitis. Assessment of conjunctival microcirculation was done by the proposed method of fluorescein angiography in which the dye is applied to the bulbar conjunctival capillary bed. RESULTS: In all cases after a microdose of fluorescein was administered to the intermediate zone capillaries it distributed into two venous systems of the AES: peripheral and prelimbal venules. Circulation time and vascular permeability (depending on the presence or absence of extravasal hyperfluorescence) were described. Angiographic patterns in healthy individuals and patients with either clinical form of uveitis appeared to differ considerably. CONCLUSIONS: Findings of the proposed noninvasive application FAG reflect the state of capillary and venular components of bulbar conjunctival microcirculatory system. Sings of increased hemoperfusion of the AES and vascular permeability were seen in patients with acute anterior uveitis, whereas in pars planitis patients vascular hyperpermeability was associated with decreased hemoperfusion of the AES. The proposed method can be used for monitoring of the inflammatory process in anterior and peripheral uveitis.

[Application fluorescein angiography for assessment of anterior eye segment hemomicrocirculation in patients with cataract and pseudoexfoliation syndrome].

OBJECTIVE: to study the state of anterior eye segment (AES) hemomicrocirculation by means of application fluorescein angiography (FAG) in patients with cataract of different maturity solely or in combination with pseudoexfoliation syndrome (PES). MATERIAL AND METHODS: A total of 58 patients (98 eyes) with cataract or cataract and PES aged from 45 to 82 years (68.4 +/- 5.2 years on average) were assessed (study group). These patients were divided into 2 subgroups: I--patients with cataract and no PES, II--patients with both cataract and PES. The control group included 15 individuals (21 eyes) without ophthalmic pathology aged from 47 to 72 years (57.7 +/- 4.7 years on average). Conjunctival microcirculation was assessed by the proposed FAG method, in which the dye is introduced directly to the bulbar conjunctival capillary bed through application. RESULTS: The following parameters of application FAG that characterize hemomicrocirculation of the AES were analyzed: venular appearance time, venous phase duration, beginning of extravasal hyperfluorescence, microvessels functionality regarding their number and caliber. All patients demonstrated hypoperfusion, the intensity of which correlated with cataract maturation and the presence of PES. CONCLUSION: Application FAG adequately reflects the state of hemomicrocirculation of the AES in cataracts and PES.