Preoperative aqueous humour flare values do not predict proliferative vitreoretinopathy in patients with rhegmatogenous retinal detachment

LASER FLARE PHOTOMETRY IN PRIMARY RHEGMATOGENOUS RETINAL DETACHMENT: An Evaluation of 2,487 Cases

PURPOSE

Exploratory analysis associated with the prospective, multicenter, randomized PRIVENT trial. To characterize the associations between laser flare photometry and anatomical and epidemiological features of rhegmatogenous retinal detachment (RRD).

METHODS

The authors measured laser flare values of all 3,048 prescreened patients excluding those with comorbidities. A mixed regression analysis evaluated the strength of the influencing factors like age, sex, lens status, and presence and extent of RRD on laser flare.

RESULTS

Rhegmatogenous retinal detachment was more frequent in men (65.8%) than in women (34.2%, P < 0.001) and in right (52%) than in left eyes (48%, P = 0.045). Phakic RRD affected less quadrants and was less likely to be associated with macula-off status than pseudophakic RRD (48.4% vs. 58.0% macula off, 23% vs. 31% ≥3 quadrants, P < 0.001). Laser flare of affected eyes was significantly higher compared with fellow eyes (12.6 ± 15.2 vs. 8.3 ± 7.4 pc/ms, P < 0.001). The factors age, sex, lens status, presence of RRD, and the number of quadrants affected were independent influencing factors on laser flare. R 2 was 0.145 for phakic and 0.094 for pseudophakic eyes.

CONCLUSION

The results indicate that there may be more factors affecting laser flare than previously assumed. This might limit flare as predictive value for PVR and retinal redetachment.

Lens status and degree of lens opacity influence laser flare photometry (objective tyndallometry)

PURPOSE

Objective tyndallometry using laser flare photometry can be utilized e.g., in management of uveitis. Previous studies showed a significant difference in flare values between pseudophakic and phakic eyes. We investigate a potential association between the degree of lens opacification and flare value in a large cohort phakic eyes.

METHODS

Retrospective, non-interventional single center study. Laser flare values of 460 healthy fellow eyes from two large cohorts (primary rhegmatogenous retinal detachment (RRD), macular holes (MH)) were correlated with lens status, degree of lens opacity, and age.

RESULTS

Out of 460 patients (mean age 64.6 ± 11.2, 57% male) 30.4% were pseudophakic (70.2 ± 10.9) and 69.6% phakic, of which 47.8% showed a clear lens (57.3 ± 9.1), 43.2% an mild cataract (65.2 ± 9.0) and 9.0% a moderate cataract (73.5 ± 9.0).In pseudophakia, flare (8.14 ± 4.6 pc/ms) was significantly higher compared to phakia (6.4 ± 3.9 pc/ms; p < 0.001). In phakic eyes, flare values increased significantly with increasing lens opacity (clear lens 5.3 ± 2.8 pc/ms; mild cataract 7.0 ± 4.0 pc/ms; moderate cataract 9.5 ± 6.1 pc/ms; p < 0.001). In clear lenses and mild cataract, age correlated significantly with flare (two-sided, p < 0.001, clear lenses R = 0.3; mild cataract R = 0.4). In clear lenses, flare values increased with age by 0.09 per year, in mild cataract by 0.17 (regression coefficients). No significant correlation was found between age and flare value in moderate cataract and pseudophakic eyes.

CONCLUSION

The level of objective tyndallometry seems to be dependent on lens status, degree of lens opacity and age. These factors should therefore be taken into account when interpreting laser flare values in the future.

Association between laser flare photometry and symptom duration in primary rhegmatogenous retinal detachment

PURPOSE

The purpose of this study was to investigate preoperative blood-ocular barrier disruption via laser flare photometry (LFP) in patients diagnosed with rhegmatogenous retinal detachment (RRD), and to analyse possible associations with symptom duration and anatomical parameters.

METHODS

We retrospectively analysed consecutive patients presenting with RRD at a single centre between January 2016 and March 2020. LFP was performed in both eyes after pupillary dilatation prior to RRD surgery. Symptom duration, extent of retinal detachment, and lens status were assessed. For statistical analysis, we carried out the unequal variances t test and Welch's analysis of variance (ANOVA).

RESULTS

We included 373 eyes of 373 patients (mean age 63.96 years ± 10.29; female:male ratio 1:1.8). LFP values quantified in photon count per millisecond (pc/ms) increased with longer symptom duration when comparing patients with a symptom duration of 0-3 days (n = 158; 9.25 ± 6.21 pc/ms) and ≥ 4 days (n = 215; 11.97 ± 11.58 pc/ms; p = 0.004). LFP values also rose with the number of retinal quadrants affected by RRD (1 quadrant, 6.82 ± 4.08 pc/ms; 2 quadrants, 10.08 ± 7.28 pc/ms; 3 quadrants, 12.79 ± 7.9 pc/ms; 4 quadrants, 31.57 ± 21.27 pc/ms; p < 0.001), macula off status (macula on, 8.89 ± 6.75 pc/ms; macula off, 12.65 ± 11.66 pc/ms; p < 0.001), and pseudophakic lens status (pseudophakia, 12.86 ± 9.52 pc/ms; phakia: 9.31 ± 9.67 pc/ms; p < 0.001).

CONCLUSION

In RRD patients, blood-ocular barrier disruption quantified by LFP is associated with the duration of symptoms and the disease's anatomical extent. These results warrant further investigation of the potential clinical use of LFP in RRD.

Translational and clinical advancements in management of proliferative vitreoretinopathy

PURPOSE OF REVIEW

Despite advancement in the surgical instrumentation and techniques, proliferative vitreoretinopathy (PVR) remains the most common cause for failure of rhegmatogenous retinal detachment (RRD) repair. This review discusses ongoing translational and clinical advancements in PVR.

RECENT FINDINGS

PVR represents an exaggerated and protracted scarring process that can occur after RRD. The primary cell types involved are retinal pigment epithelium, glial, and inflammatory cells. They interact with growth factors and cytokines derived from the breakdown of the blood-retinal barrier that trigger a cascade of cellular processes, such as epithelial-mesenchymal transition, cell migration, chemotaxis, proliferation, elaboration of basement membrane and collagen and cellular contraction, leading to overt retinal pathology. Although there are currently no medical therapies proven to be effective against PVR in humans, increased understanding of the risks factors and pathophysiology have helped guide investigations for molecular targets of PVR. The leading therapeutic candidates are drugs that mitigate growth factors, inflammation, and proliferation are the leading therapeutic candidates.

SUMMARY

Although multiple molecular targets have been investigated to prevent and treat PVR, none have yet demonstrated substantial evidence of clinical benefit in humans though some show promise. Advancements in our understanding of the pathophysiology of PVR may help develop a multipronged approach for this condition.

Clinical factors contributing to postoperative aqueous flare intensity after 27-gauge pars plana vitrectomy for the primary rhegmatogenous retinal detachment

PURPOSE

To investigate the perioperative clinical factors, which contribute to the postsurgical aqueous flare intensity (AFI) following 27-gauge pars plana vitrectomy (27GPPV) for primary rhegmatogenous retinal detachment (RRD).

STUDY DESIGN

Retrospective clinical study.

METHODS

We performed retrospective analyses of the medical records of 47 eyes of 47 patients with primary RRD who had undergone 27GPPV with a wide-angle viewing system. AFI was measured preoperatively and 1 week, 1 month, 3 months, 6 months, and 12 months after the surgery.

RESULTS

AFI was significantly increased 1 week after the surgery (p<0.01) and then decreased overtime. At 6 months after surgery it was still statistically significantly higher than preoperative AFI (p=0.03). There was no statistical difference between preoperative AFI and that at 12 months following surgery. Multiple regression analyses revealed that the number of retinal photocoagulations and the performance of scleral indentation had significant positive correlation with AFI at 1 week, 1 month, 3 months, and 6 months, and at 1 month and 3 months after the surgery, respectively.

CONCLUSION

Intraoperative retinal photocoagulation and scleral indentation are probable causes of increased AFI after 27G PPV for RRD.

Ocular Spot Fluorometer Equipped With a Lock-In Amplifier for Measurement of Aqueous Flare

Purpose

To evaluate a custom-made ocular fluorometer for detection of intensity of light scatter (ILS) from the anterior chamber (A/C) as an objective measure of aqueous flare.

Methods

The fluorometer, equipped with a lock-in amplifier, was employed in the scatter mode to detect ILS from A/C. Measurements were performed with two illumination slit widths of 0.5 and 0.25 mm. The axial resolution at these slit widths were 80 and 200 μm, respectively. Healthy and pseudophakic eyes, with grade 0 Standardization of Uveitis Nomenclature (SUN) score, were employed as control subjects. ILS was also recorded in a cohort of patients who had undergone phacoemulsification and showed grades 1+ or 2+ on postoperative days 1 and 4.

Results

The inter- and intraobserver variabilities in the measurement of ILS were not significant. In cataract patients, ILS was significantly higher on postoperative day 1 relative to healthy eyes. By day 4, ILS decreased significantly and was only marginally different from ILS in quiet pseudophakic eyes or healthy eyes. Eyes with higher SUN scores showed proportionately increased ILS. The receiver-operator characteristic analysis indicated no advantage in using the smaller slit width in discriminating ILS at different SUN scores although it provided higher axial resolution.

Conclusions

The lock-in–based spot fluorometer is reliable for measurement of ILS with high precision and accuracy.The measured ILS correlates linearly with SUN scores and can be used to provide a higher granularity for recording aqueous flare.

Translational Relevance

The instrument can be used in the clinical management of uveitis and drug development toward uveitis.

Postoperative aqueous humour flare as a surrogate marker for proliferative vitreoretinopathy development

PURPOSE

As some surgical procedures have been shown to increase postoperative flare values and thus contribute to blood-ocular barrier breakdown, retinal reattachment surgery might influence the risk of developing proliferative vitreoretinopathy (PVR). Therefore, we investigated whether postoperative aqueous flare values are a surrogate marker for the development of postoperative PVR.

METHODS

We prospectively included 195 patients with primary rhegmatogenous retinal detachment (RRD) and measured aqueous laser flare preoperatively, and at 2 and 6 weeks postoperatively. Postoperative PVR was defined as reoperation for redetachment due to PVR membranes, within 6 months of initial surgery. Logistic regression and receiver operating characteristic (ROC) analysis determined whether higher postoperative flare values were associated with an increased risk of developing PVR later on.

RESULTS

Reoperation for postoperative PVR was needed in 12 (6.2%) patients; in 18 (9.2%), reoperation was not related to PVR. The median flare value for patients who would develop PVR was significantly higher than that of patients who would not develop PVR, both at 2 weeks (p = 0.001) and 6 weeks (p < 0.001) postoperatively. Logistic regression analyses showed that a higher flare value significantly increased the odds of developing PVR, either at 2 weeks [odds ratio (OR) 1.027; 95% CI: 1.010-1.044] or 6 weeks (OR 1.076; 95% CI: 1.038-1.115).

CONCLUSION

Flare values both at 2 and 6 weeks postoperatively seem a good surrogate marker in terms of sensitivity and specificity for the development of postoperative PVR but have only a modest positive predictive value. The 2-week value would be more useful in terms of early recognition of high-risk patients and hence give the possibility to better study effects of treatment methods.

Does the disruption of horizontal anterior ciliary vessels affect the blood-aqueous barrier function?

PURPOSE

To investigate the significance of the anterior ciliary vessels (ACVs) preservation during the conventional horizontal strabismus surgery.

METHODS

Patients (≥ 8 years) with horizontal strabismus were randomly allocated into group 1 (with ACV preservation) and group 2 (without ACV preservation). The surgical eyes in group 1 were further divided into group A (one rectus muscle operated) and group B (two rectus muscles operated). Similarly, eyes in group 2 were divided into group C (one rectus muscle operated) and group D (two rectus muscles operated). The success rate of ACV preservation was calculated. The anterior chamber flare measurements of each eye by laser flare photometry were recorded on the day prior to and after operation. The flare values between groups and between pre- and post-operation in each group were compared by one-way analysis of variance and a paired t-test respectively.

RESULTS

In groups A and B, the success rate of ACV preservation was 82% (27/33) and 70% (28/40)respectively, and the flare values between pre- and post-operation showed no significant differences(4.378 ± 1.527, 4.544 ± 1.452, P = 0.526; 4.625 ± 1.090, 4.989 ± 1.468, P = 0.101 respectively). However, the postoperative values were significantly increased in group C and group D(4.661 ± 1.031, 5.039 ± 1.310, P = 0.025; 4.933 ± 1.691, 5.502 ± 1.430, P = 0.000 respectively). The postoperative flare readings of group D were significantly higher than group B, while group A and group C had no significant variation.

CONCLUSION

ACV preservation probably has clinical significance in reducing the undesirable influence on the blood-aqueous barrier.