Laser flare-cell photometer: principle and significance in clinical and basic ophthalmology

The progress and future of corneal endothelial transplantation

Endothelial transplantation has recently been accepted worldwide, in the long history of corneal transplantation. The introduction of endothelial keratoplasty (Descemet stripping automated endothelial keratoplasty and Descemet membrane endothelial keratoplasty) has enabled us to expand the surgical indications owing to the low incidence of rejection and quick recovery of visual function. New technologies have been developed to ensure stable postoperative outcomes with a shorter learning curve, such as transplantation using cultured human endothelial cells and induced pluripotent stem cells (iPS) or new devices such as artificial endothelium. This review discusses the history and characteristics of corneal transplantation alongside new treatment options that may offer hope for patients with endothelial disease in the future.

Implications of Ocular Confounding Factors for Aqueous Humor Proteomic and Metabolomic Analyses in Retinal Diseases

Purpose

To assess the impact of ocular confounding factors on aqueous humor (AH) proteomic and metabolomic analyses for retinal disease characterization.

Methods

This study recruited 138 subjects (eyes): 102 with neovascular age-related macular degeneration (nAMD), 18 with diabetic macular edema (DME), and 18 with cataract (control group). AH samples underwent analysis using Olink Target 96 proteomics and Metabolon's metabolomics platform Data analysis included correlation, differential abundance, and gene-set analysis.

Results

In total, 756 proteins and 408 metabolites were quantified in AH. Total AH protein concentration was notably higher in nAMD (3.2-fold) and DME (4.1-fold) compared to controls. Pseudophakic eyes showed higher total AH protein concentrations than phakic eyes (e.g., 1.6-fold in nAMD) and a specific protein signature indicative of matrix remodeling. Unexpectedly, pupil-dilating drugs containing phenylephrine/tropicamide increased several AH proteins, notably interleukin-6 (5.4-fold in nAMD). Correcting for these factors revealed functionally relevant protein correlation clusters and disease-relevant, differentially abundant proteins across the groups. Metabolomics analysis, for which the relevance of confounder adjustment was less apparent, suggested insufficiently controlled diabetes and chronic hyperglycemia in the DME group.

Conclusions

AH protein concentration, pseudophakia, and pupil dilation with phenylephrine/tropicamide are important confounding factors for AH protein analyses. When these factors are considered, AH analyses can more clearly reveal disease-relevant factors.

Translational Relevance

Considering AH protein concentration, lens status, and phenylephrine/tropicamide administration as confounders is crucial for accurate interpretation of AH protein data.

Inflammatory reaction in eyes with late in-the-bag intraocular lens dislocation

PURPOSE

To investigate the inflammatory reaction in eyes with late in-the-bag intraocular lens (IOL) dislocation.

METHODS

This prospective clinical study with fellow-eye comparison consists of 76 of the patients (76 eyes) with late in-the-bag IOL dislocation enrolled in the LION trial. The main outcome measure was anterior chamber flare before surgery measured with a laser flare meter in photon counts per millisecond (pc/ms). The dislocation was graded as 1 (small: optic still covering the visual axis), 2 (optic equator close to the visual axis) or 3 (optic decentred beyond the visual axis, but the IOL-capsule complex partly visible in the pupillary area). The secondary aim was to compare intraocular pressure (IOP) before surgery.

RESULTS

Flare levels before surgery were significantly higher in the dislocation eyes than in the fellow eyes with a median flare of 21.5 (range 5.4-135.7) pc/ms versus 14.1 (2.0-42.9) pc/ms, respectively (p ˂ 0.001). A regression analysis of log-transformed flare values showed that the dislocation eyes had a non-significant tendency towards higher flare in dislocation grade 1 with a median flare of 24.6 (5.4-135.7) pc/ms compared to grade 2; 19.6 (6.5-41.5) pc/ms (p = 0.06), and no significant difference compared to grade 3; 19.4 (10.2-53.5) pc/ms (p = 0.47). The IOP was significantly higher in the dislocation eyes than in the fellow eyes (p ˂ 0.001).

CONCLUSIONS

Eyes with late in-the-bag IOL dislocation had increased flare levels compared to their fellow eyes. This suggests that inflammation is part of the clinical picture of late in-the-bag IOL dislocation.

Laser Flare Photometry to Monitor Childhood Chronic Uveitis: A Preliminary Report of a Monocentric Italian Experience

Background: Childhood chronic non-infectious uveitis (cNIU) is a challenging disease that needs close monitoring. Slit lamp evaluation (SLE) is the cornerstone of ophthalmological evaluation for uveitis, but it is affected by interobserver variability and may be problematic in children. Laser flare photometry (LFP), a novel and objective technique, might be used in children with uveitis. Aim: The aim of this study was to attempt the use of LFP in cNIU clinical practice. Methods: Children, attending the Rheumatology Unit and who were scheduled to receive ophthalmological evaluation, were prospectively enrolled to concomitantly receive SLE and LFP. SLE was performed blind to LFP measure. Demographic, laboratory, clinical, and ophthalmology data were collected. Results: A total of 29 children (58 eyes) were enrolled, including 3 with juvenile idiopathic arthritis without uveitis (JIA-no-U), 15 with JIA-associated uveitis (JIA-U), and 11 with idiopathic chronic uveitis (ICU). We observed significantly higher LFP values in the eyes of children with uveitis compared to the others (10.1 IQR 7.1-13.6 versus 6.2 IQR 5.8-6.9, p = 0.007). Accordance between the SLE and LFP measures, at baseline (ρ.498, p < 0.001) and during the follow-up (LFP II ρ 0.460, p < 0.001, LFP III ρ 0.631, p < 0.001, LFP IV ρ 0.547, p = 0.006, LFP V ρ 0.767, p = 0.001), was detected. We evaluated significant correlation between LFP values and the presence of complications (ρ 0.538, p < 0.001), especially with cataract formation (ρ 0.542, p < 0.001). Conclusions: In this cohort, LFP measurements showed a good correlation with SLE. LFP values showed a positive correlation with the presence of complications. LFP might be considered as a reliable objective modality to monitor intraocular inflammation in cNIU.

Ex-PRESS Implantation versus Trabeculectomy for Long-Term Maintenance in Patients with Open-Angle Glaucoma

Purpose

To compare the efficacy of Ex-PRESS implantation (EXP) with that of trabeculectomy (TLE) with mitomycin C for maintaining low target intraocular pressure (IOP) in patients with open-angle glaucoma.

Patients and Methods

Patients were randomly assigned to receive EXP or TLE. Surgical success was defined according to three target mean IOP ranges (5 mmHg ≤ IOP ≤ 18 mmHg [criterion A], 5 mmHg ≤ IOP ≤ 15 mmHg [criterion B], and 5 mmHg ≤ IOP ≤ 12 mmHg [criterion C]) representing reductions of at least 20% below the baseline on two consecutive follow-up visits 3 months post-surgery, with or without antiglaucoma medication and without further glaucoma surgery. Participants were divided into three subgroups based on baseline mean deviation (MD) values: early (MD ≥ -6 dB), moderate (-6 dB > MD ≥ -12 dB), and advanced (-12 dB > MD). Survival rates were calculated by subgroup.

Results

A total of 73 patients, including 30 in the EXP group and 43 in the TLE group, were included in the study. No significant differences in baseline ocular or demographic characteristics were found between the two groups. No significant difference in IOP was noted every 6 months. After the 3-year follow-up, success rates were A) 60.0% and 60.2%, B) 45.7% and 58.1%, and C) 31.5% and 40.5% for the EXP and TLE groups, respectively. Moreover, there was no difference in success rate based on glaucoma level. Many glaucoma medications administered before surgery were associated with a higher failure rate in the TLE group but not in the EXP group.

Conclusion

Both procedures resulted in similar IOP reductions and success rates for a low target IOP. The number of preoperative glaucoma medications was a risk factor for TLE failure.

The effect of one- and two-rectus muscle strabismus surgery on anterior chamber flare

PURPOSE

To investigate the effect of the most commonly performed strabismus surgery procedures on the blood-aqueous barrier using laser flare photometry (LFP).

METHODS

Patients who underwent unilateral or bilateral strabismus surgery between January 2020 and May 2021 were included. Eyes were grouped according to the number of rectus muscles operated: one rectus muscle procedure (recession) with or without inferior oblique anterization (IOA), ipsilateral two rectus muscle procedure (recession and resection) with or without IOA, and unoperated fellow eyes of patients undergoing unilateral surgery. Anterior chamber flare values were measured by LFP for each eye the day before the surgery and day 1, week 1, and month 1 postoperatively.

RESULTS

A total of 66 eyes of 33 patients (21 females) were included. There were 29 eyes in the one-muscle group, 22 in the two-muscle group, and 15 in the fellow-eye group. The mean flare values of the two-muscle group were significantly higher than those of the other groups at postoperative day 1 and week 1 (P = 0.001, for both). The mean postoperative day 1, week 1, and month 1 flare values of the two-muscle group were significantly higher than the mean preoperative flare value. There were no significant differences between pre- and postoperative flare values of the one-muscle or fellow-eye groups (P > 0.05, for both).

CONCLUSIONS

In our study cohort, LFP provided evidence of subclinical changes in the blood-aqueous barrier up to the first month postoperatively in otherwise healthy patients undergoing two-muscle surgery compared with those undergoing one-muscle surgery and unoperated fellow eyes.

The Blood-ocular Barriers and their Dysfunction: Anatomy, Physiology, Pathology

Complex barriers comprise the blood-aqueous (BAB) and the blood-retinal barrier (BRB), and separate anterior and posterior eye chambers, vitreous body, and sensory retina from the circulation. They prevent pathogens and toxins from entering the eye, control movement of fluid, proteins, and metabolites, and contribute to the maintenance of the ocular immune status. Morphological correlates of blood-ocular barriers are tight junctions between neighboring endothelial and epithelial cells, which function as gatekeepers of the paracellular transport of molecules, thereby limiting their uncontrolled access to ocular chambers and tissues. The BAB is composed of tight junctions between endothelial cells of the iris vasculature, endothelial cells of Schlemm's canal inner wall, and cells of the nonpigmented ciliary epithelium. The BRB consists of tight junctions between endothelial cells of the retinal vessels (inner BRB) and epithelial cells of the retinal pigment epithelium (outer BRB). These junctional complexes respond rapidly to pathophysiological changes, thus enabling vascular leakage of blood-derived molecules and inflammatory cells into ocular tissues and chambers. Blood-ocular barrier function, which can be clinically measured by laser flare photometry or fluorophotometry, is compromised in traumatic, inflammatory, or infectious processes, but also frequently contributes to the pathophysiology of chronic diseases of the anterior eye segment and the retina, as exemplified by diabetic retinopathy and age-related macular degeneration.

Association between blood-aqueous barrier disruption and extent of retinal detachment

PURPOSE

To investigate the association between anatomical features of rhegmatogenous retinal detachment (RRD) and the extent of blood-aqueous barrier disorder measured by non-invasiv laser flare photometry.

METHODS

Retrospective evaluation of consecutive patients with RRD that underwent surgery between November 2016 and October 2018. Descriptive evaluation of pre- and postoperative parameters and correlation to preoperative laser flare value, extent of retinal detachment and re-detachment rate were performed.

RESULTS

266 patients (mean age 62.73 ± 10.40 years, 62.8% male) were included. Mean preoperative flare value was 11.0 ± 11.9 pc/ms. In pseudophakia flare values were higher than in phakia (12.7 ± 10.4 pc/ms versus 9.8 ± 12.9 pc/ms; p = 0.042). Flare increased and correlated significantly with the number of affected retinal quadrants (Q) (1 Q 6.4 ± 3.3 pc/ms; 2 Q 10.5 ± 8.8 pc/ms; 3 Q 15.6 ± 9.1 pc/ms; 4 Q 27.5 ± 33.3 pc/ms; p < 0.001; r = 0.40). Macular status correlated significantly with flare values (macula on 8.6 ± 7.1 pc/ms, off 13.1 ± 15.0 pc/ms; p = 0.004; r = 0.17).

CONCLUSION

The level of objective tyndallometry in RRD seems to be influenced by lens status and extent of retinal detachment. Thus, the greater the affected retinal area is, the more blood-aqueous barrier disruption seems to be present.

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.

The Immediate Early Response of Lens Epithelial Cells to Lens Injury

Cataracts are treated by lens fiber cell removal followed by intraocular lens (IOL) implantation into the lens capsule. While effective, this procedure leaves behind numerous lens epithelial cells (LECs) which undergo a wound healing response that frequently leads to posterior capsular opacification (PCO). In order to elucidate the acute response of LECs to lens fiber cell removal which models cataract surgery (post cataract surgery, PCS), RNA-seq was conducted on LECs derived from wild type mice at 0 and 6 h PCS. This analysis found that LECs upregulate the expression of numerous proinflammatory cytokines and profibrotic regulators by 6 h PCS suggesting rapid priming of pathways leading to inflammation and fibrosis PCS. LECs also highly upregulate the expression of numerous immediate early transcription factors (IETFs) by 6 h PCS and immunolocalization found elevated levels of these proteins by 3 h PCS, and this was preceded by the phosphorylation of ERK1/2 in injured LECs. Egr1 and FosB were among the highest expressed of these factors and qRT-PCR revealed that they also upregulate in explanted mouse lens epithelia suggesting potential roles in the LEC injury response. Analysis of lenses lacking either Egr1 or FosB revealed that both genes may regulate a portion of the acute LEC injury response, although neither gene was essential for expression of either proinflammatory or fibrotic markers at later times PCS suggesting that IETFs may work in concert to mediate the LEC injury response following cataract surgery.

A case of intraocular inflammation after intravitreal brolucizumab injection monitored by laser flare-cell photometer

Purpose

To report the efficacy of combination therapy using intravitreal injection of brolucizumab (IVbr) and sub-Tenon's injection of triamcinolone acetonide (STTA) and of monitoring with a laser flare-cell photometer (LFP) in a case of polypoidal choroidal vasculopathy (PCV) with intraocular inflammation (IOI).

Observations

A 72-year-old Japanese woman with PCV had her treatment switched to IVbr due to being refractory to aflibercept. Two weeks after starting IVbr, her visual acuity (VA) declined to 0.40 from 0.10 logarithm of the minimum angle of resolution (logMAR) VA at baseline. In addition, the LFP flare increased to 51.2 photon count/ms (pc/ms) compared with the baseline of 16.1 pc/ms. We diagnosed her with the onset of IOI and immediately started treatment with sub-Tenon's injection of 20 mg triamcinolone acetonide (STTA). Two weeks after receiving STTA, her VA had recovered to 0.15 logMAR, and the LFP flare had decreased to 17.9 pc/ms with dry macula. Eight weeks after the first IVbr treatment, the logMAR VA had improved to −0.18 with achievement of dry macula and stabilization of the LFP flare at 12.2 pc/ms. We administered combined therapy using IVbr and STTA to our patient, and 12 weeks later, the logMAR VA remained at 0.00 with dry macula and 18.1 pc/ms for LFP flare. We continued combination therapy, and after 8 months, her logMAR VA remained at −0.08, and optical coherence tomography showed dry macula, while the LFP flare had stabilized at 16.6 pc/ms.

Conclusions and Importance

Combination therapy of IVbr and STTA stabilized IOI and achieved dry macula. The LFP flare score clearly showed the degree of and changes in inflammation.

Correlation of Clinical Aqueous Flare Grading to Semi-Automated Flare Measurements Using Laser Flare Photometry

PURPOSE

To compare laser flare photometry (LFP) measurements of aqueous flare with Standardization of Uveitis Nomenclature (SUN) and modified SUN grading.

METHODS

In this prospective study with multicenter design, uveitis patients were classified according to SUN and modified SUN grading scales. LFP was performed with Kowa FM-700 flaremeter. Mean LFP values were compared with SUN and MSUN scores.

RESULTS

The study included 475 LFP measurements, of which 216, 48, 150, 31, 28 and 2 had 0, 0.5+, 1+, 1.5+, 2+ and 3+ flare, respectively. LFP values were significantly different between each two consecutive steps for both clinical gradings (all P < .05). Cut-off values for modified SUN grading steps were defined as 5.7, 9.7, 15.7 and 43.2 for 0/0.5+, 0.5+/ 1+, 1+/1.5+ and 1.5/2+ borders of clinical flare, respectively.

CONCLUSIONS

LFP proves to be an objective measurement in analyzing aqueous flare comparable to both SUN and MSUN clinical grading systems.

The ocular findings related to oral bisphosphonate use

OBJECTIVE

We aimed to investigate ocular involvement findings in female osteoporosis patients using oral bisphosphonate (BP).

METHODS

A total of 51 female osteoporosis patients aged 50-75 years using oral BP for at least one year for the study group and 64 age-matched non-osteoporosis female patients for the control group were included in the study. The BP type and exposure time were noted. The ophthalmic examination findings and measurements of the flare of the patients who received oral BP due to osteoporosis and the controls were evaluated.

RESULTS

The mean duration of BP use was 3.96 years. In the study group, it was detected four of 51 patients were diagnosed with meibomian gland dysfunction (MGD) (7.8%), seven of 102 eyes had erythematous, irregular, thickened lid margin or telangiectasia around the glandular orifices. There were no pathological findings on fundus examination. The mean value of measurements of the flare (ph/ms) was 7.90±7.96 in the study group, and 5.02±0.81 in the control group. When the mean values were compared, there was a significant difference between the two groups (P=.001). A significant difference was found in the mean value of measurements of the flare between the patients using alendronate, and ibandronate with the control group (P=.001; P=.005, respectively).

CONCLUSION

Our study showed that the flare in the anterior chamber associated with chronic ocular inflammation can be seen higher rate in patients using oral alendronate, and ibandronate compared to those who do not. Morever it can be said that oral BPs may cause similar ocular side effects like as intravascular BPs.

Effect of light backscattering from anterior segment structures on automated flare meter measurements

BACKGROUND

To evaluate effect of maximal anterior cortical lens density, iris scatter and anterior chamber depth on laser flare photometry.

METHODS

Patients diagnosed with clinical uveitis were enrolled in the study. Clinical flare gradings were recorded upon the Standardization of Uveitis Nomenclature. Aqueous flare was measured with an automated device (Kowa FM-700). Back-scattering from anterior cortical lens and anterior iris surface was calculated from Scheimpflug images. A curvilinear regression model was used to calculate estimated values for each clinical grade. These values were used to split cases in Group I (laser flare photometry lower than estimated) and Group II (laser flare photometry higher than estimated). Mean anterior chamber depth, pupil aperture, maximal anterior cortical lens density and iris scatter values were compared between two groups. A stepwise multiple regression analysis was performed to determine the effect of clinical flare gradings and ocular parameters on aqueous flare measurements.

RESULTS

The study included 228 eyes of 114 cases. Scheimpflug images were obtained from 105 eyes. Estimated aqueous flare measurements (in photons/milliseconds) were 4.87, 8.50, 14.81, 25.83, 45.04 and 136.93 for 0, 0.5+, 1+, 1.5+, 2+ and 3+ clinical flare respectively. Group II had higher maximal anterior cortical lens density than Group I (96.6 ± 37.1 vs 77.9 ± 17.1 pixel unit, p = 0.001). The measured aqueous flare was significantly related to clinical flare, maximal anterior cortical lens density and pupil aperture (adjusted R2: 0.480, p < 0.001).

CONCLUSION

The back-scattered light from anterior cortical lens could affect laser flare photometry measurements. This effect might be quantified by Scheimpflug imaging.

Intraocular Inflammation in Eyes Operated for Late In-the-bag intraOcular lens dislocatioN (LION): A Randomized Clinical Trial

PURPOSE

To compare the intraocular inflammation after 2 surgical approaches for late in-the-bag intraocular lens (IOL) dislocation.

DESIGN

Prospective, randomized, parallel-group clinical trial.

METHODS

We randomly assigned 100 patients (100 eyes) referred to Oslo University Hospital (tertiary referral center) with late in-the-bag IOL dislocation into IOL repositioning by scleral suturing (n=49) or IOL exchange with retropupillary fixation of an iris-claw lens (n=51). Patients were examined before surgery and 2 weeks, 6 weeks, and 6 months after surgery. The main outcome measure was anterior chamber laser flare, measured with a laser flare meter as photon counts per millisecond (pc/ms).

RESULTS

Two weeks following surgery, median flare values were 28.9 pc/ms (range, 7.9-140) in the repositioning group and 31.6 pc/ms (range, 9.8-92.3) in the exchange group (P = .83). Flare levels were still elevated after 6 weeks with no difference between the groups (P = .93), whereas it decreased to baseline levels after 6 months. Six weeks following surgery, the central retinal thickness was similar (P = .97); cystoid macular edema (CME) was found in 4 and 5 patients, respectively (P = .85); and the mean best corrected visual acuity was 0.17 (95% CI 0.09, 0.25) and 0.21 (95% CI 0.09, 0.32) logarithm of the minimum angle of resolution, respectively (P = .61).

CONCLUSIONS

This study revealed similar levels of intraocular inflammation following IOL repositioning and IOL exchange. There was no significant difference regarding risk of CME and visual outcome. The prolonged elevation in postoperative flare indicates a possible requirement for an extended anti-inflammatory treatment period after these operations.

Reliability of Aqueous Flare Measurements During Uveitis by a Spot Fluorometer

Purpose: To evaluate the reliability of intensity of light scatter (ILS) for diagnosing mild-to-moderate uveitis, which is difficult to score by the subjective standardized uveitis nomenclature (SUN) grading. Methods: ILS (in millivolts) was measured in healthy subjects and uveitis patients by a custom-made Spot fluorometer. The reliability was assessed by noise analysis of the instrument using turbid samples and intra- and interobserver variabilities. Results: ILS increased with the severity of inflammation: healthy (0.1498 ± 0.0564) and SUN0 (0.1590 ± 0.0564) < SUN1+ (0.2050 ± 0.0887) < SUN2+ (0.4283 ± 0.1895). The increase in ILS was more significant between healthy and SUN1+ (P < 0.0001) compared to the difference between SUN0 and SUN1+ (P = 0.0006). The instrument noise was small (σ = 0.002). Intraobserver measurements revealed no variability (P > 0.98) between measurements and predicted repeatability coefficients of 0.0754, 0.0522, and 0.0532 in healthy, SUN0, and SUN1+, respectively. Interobserver measurements also showed no variability (P > 0.88) and predicted intraclass correlation coefficient > 0.63 in healthy and uveitis subjects. Conclusions: The fluorometer enables precise measurement of ILS with negligible instrument noise, and the measurements are unaffected by intra- and interobserver variabilities. However, the difference in mean ILS between SUN0 and SUN1+ is greater than the instrument noise and comparable to intra- and interobserver variabilities. Thus, ILS measurements are likely impacted by blinking, eye movements, and focusing jitter. The impact of these factors must be reduced before using the fluorometer to distinguish mild-to-moderate uveitis.

Non-invasive Instrument-Based Tests for Quantifying Anterior Chamber Flare in Uveitis: A Systematic Review

Purpose: Anterior chamber (AC) flare is a key sign for anterior uveitis. New instrument-based techniques for measuring AC flare can offer automation and objectivity. This review aims to identify objective instrument-based measures for AC flare.Methods: In this systematic review, we identified studies reporting correlation between instrument-based tests versus clinician AC flare grading, and/or aqueous protein concentration, as well as test reliability.Results: Four index tests were identified in 11 studies: laser-flare photometry (LFP), optical coherence tomography, ocular flare analysis meter (OFAM) and the double-pass technique. The correlation between LFP and clinician grading was 0.40-0.93 and 0.87-0.94 for LFP and protein concentration. The double-pass technique showed no correlation with clinician grading and insufficient information was available for OFAM.Conclusion: LFP shows moderate to strong correlation with clinician grading and aqueous protein concentration. LFP could be a superior reference test compared to clinician AC flare grading for validating new index tests.

Corneal Thickness and Anterior Chamber Flare After Cataract Surgery: A Randomized Controlled Trial Comparing Five Regimens for Anti-Inflammatory Prophylaxis

Purpose

To investigate the relationship between early post-operative anterior chamber inflammation (aqueous flare) and central corneal thickness (CCT) after cataract surgery and to evaluate the effect of anti-inflammatory prophylaxis on CCT.

Setting

Department of Ophthalmology, Rigshospitalet-Glostrup, University Hospital Copenhagen, Denmark.

Design

Post-hoc analysis of a prospective randomized controlled trial.

Patients and Methods

A total of 470 participants who underwent standard cataract surgery were randomly allocated to prophylactic treatment with nonsteroidal anti-inflammatory drug (NSAID, groups C and D) or a combination of NSAID and steroid eye drops (groups A and B), commenced either pre-operatively (A and C) or post-operatively on the day of surgery (B and D), or "drop-less surgery" (peri-operative subtenon depot of dexamethasone, group E). Aqueous flare was measured before and three days after surgery. CCT was measured before surgery, three days, three weeks, and three months after surgery. Data were analyzed according to the intention-to-treat method.

Results

Doubling of aqueous flare increased mean CCT by 15.6 microns (95% CI 9.8; 21.3, P<0.001) three days after surgery. Mean CCT increased from 549 microns (95% CI 545; 552) at baseline to 594 microns (95% CI 585; 602) three days after surgery and returned to 551 microns (95% CI 545; 557) three months after surgery. Mean CCT was thinner in group C compared to group A three days after surgery. No difference was found for any other groups or time points.

Conclusion

Increased anterior chamber inflammation was associated with significant corneal thickening three days after cataract surgery. Choice of anti-inflammatory regimen seemed to be of no or minimal importance on CCT when the effect of inflammation was accounted for. Corneal thickening is possibly mediated by underlying deterioration of the blood-aqueous barrier and corneal endothelium pump function caused by a post-operative inflammatory response.

Morphological alternation and influence of aqueous flare in idiopathic epiretinal membrane

Background

Idiopathic epiretinal membrane (iERM) is a common retinal disease in the elderly population. The exact pathogenesis of iERM is unknown. The present study aimed to evaluate the relationship between aqueous flare and morphology of iERM using swept-source optical coherence tomography (OCT).

Methods

A consecutive series of 36 eyes of 33 patients with iERM and 109 control eyes of 109 patients were retrospectively examined. Aqueous flare measurements and OCT images were obtained on the same day. The average total retinal, inner retinal, outer retinal, and choroidal thicknesses were calculated using the thickness map mode with an Early Treatment Diabetic Retinopathy Study nine-zone grid that was divided into three zones. The maximum depth of the retinal folds in iERMs was manually measured. The correlation among flare value, maximum depth of folds, and retinal and choroidal thicknesses was evaluated. The morphological changes between the control eyes and the eyes with iERM in different stages were examined.

Results

The result demonstrated a significant positive correlation between the aqueous flare value and total and inner retinal thicknesses in the early stage of iERM. There was a significant positive correlation between the maximum depth of folds and total and inner retinal thicknesses in the early stage of iERM, and the maximum depth of folds significantly increased in the advanced stage. The total and inner retinal thicknesses and proportion of inner retinal thickness significantly increased as the stage of iERM progressed.

Conclusions

The aqueous flare value was associated with retinal thickness in the early stage of iERM, which supports the idea that inflammation or breakdown of blood–ocular barrier is involved in the process of iERM formation. The maximum retinal folds increased as the stage of iERM progressed and retinal thickness increased, which indicates that the tangential force increases as the iERM stage progresses.

Effect of anti-inflammatory regimen on early postoperative inflammation after cataract surgery

PURPOSE

To investigate whether a combination of topical nonsteroidal anti-inflammatory drugs (NSAIDs) and steroids were superior in controlling early postoperative inflammation after cataract surgery compared with topical NSAIDs alone and with dropless surgery where a sub-Tenon depot of steroid was placed during surgery.

SETTING

Department of Ophthalmology, Rigshospitalet-Glostrup, Denmark.

DESIGN

Prospective randomized controlled trial with masked statistical analyses.

METHODS

Patients undergoing phacoemulsification for age-related cataract were randomized to 1 of 5 regimens: ketorolac and prednisolone eyedrops combined (Pred+NSAID-Pre [control group] and Pred+NSAID-Post group) vs ketorolac monotherapy (NSAID-Pre and NSAID-Post groups) vs sub-Tenon depot of dexamethasone (dropless group). Drops were used until 3 weeks postoperatively, starting 3 days preoperatively in the Pre groups and on the day of surgery in the Post groups. Aqueous flare was measured at baseline and 3 days postoperatively.

RESULTS

Four hundred fifty-six participants, with a mean age of 72.1 (SD 7.0) years and 283 (62%) women, were included. Flare increased significantly more in the dropless group compared with the control group (Pred+NSAID-Pre), but none of the other groups differed significantly from the control group. Intraocular pressure decreased in all groups but significantly less in groups receiving prednisolone eyedrops (Pred+NSAID-Pre and Pred+NSAID-Post groups) compared with NSAID monotherapy and dropless groups. No differences in postoperative visual acuity were found compared with the control group.

CONCLUSIONS

No differences were found between groups randomized to NSAID monotherapy or combination of NSAID and steroid in controlling early inflammation after cataract surgery, but sub-Tenon depot of dexamethasone was less efficient. Initiating prophylactic eyedrops prior to surgery did not influence early postoperative anterior chamber inflammation.

Intravitreal autologous mesenchymal stem cell transplantation: a non-randomized phase I clinical trial in patients with retinitis pigmentosa

Background

Retinitis pigmentosa (RP) is a progressive inherited retinal disease with great interest for finding effective treatment modalities. Stem cell-based therapy is one of the promising candidates. We aimed to investigate the safety, feasibility, and short-term efficacy of intravitreal injection of bone marrow-derived mesenchymal stem cells (BM-MSCs) in participants with advanced stage RP.

Methods

This non-randomized phase I clinical trial enrolled 14 participants, categorized into three groups based on a single dose intravitreal BM-MSC injection of 1 × 10⁶, 5 × 10⁶, or 1 × 10⁷ cells. We evaluated signs of inflammation and other adverse events (AEs). We also assessed the best corrected visual acuity (BCVA), visual field (VF), central subfield thickness (CST), and subjective experiences.

Results

During the 12-month period, we noticed several mild and transient AEs. Interestingly, we found statistically significant improvements in the BCVA compared to baseline, although they returned to the baseline at 12 months. The VF and CST were stable, indicating no remarkable disease progression. We followed 12 participants beyond the study period, ranging from 1.5 to 7 years, and observed one severe but manageable AE at year 3.

Conclusion

Intravitreal injection of BM-MSCs appears to be safe and potentially effective. All adverse events during the 12-month period required observation without any intervention. For the long-term follow-up, only one participant needed surgical treatment for a serious adverse event and the vision was restored. An enrollment of larger number of participants with less advanced RP and long-term follow-up is required to evaluate the safety and efficacy of this intervention.

Trial registration

ClinicalTrials.gov, NCT01531348. Registered on February 10, 2012

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-020-02122-7.

The effects of tropicamide and cyclopentolate hydrochloride on laser flare meter measurements in uveitis patients: a comparative study

PURPOSE

To investigate the effects of 1% cyclopentolate hydrochloride and 1% tropicamide eye drops on aqueous flare measurements by using the laser flare meter.

METHODS

One hundred forty eight eyes of 83 patients with inactive uveitis were enrolled. The patients were randomly assigned to receive either 1% tropicamide (Group 1) or 1% cyclopentolate hydrochloride (Group 2) as the mydriatic agent. Best corrected visual acuity (BCVA), intraocular pressure (IOP), aqueous flare reaction levels measured by laser flare meter device (FM 600, Kowa, Kowa Company Ltd, Nagoya, Japan) before and post dilatation agents were evaluated.

RESULTS

Group 1 consisted of 75 eyes and Group 2 consisted of 77 eyes. The mean age of Group 1 patients was 34.85 ± 12.60 (range, 12-64) years; the mean age of Group 2 was 36.92 ± 13.30 (range, 12-70) years (p > 0.05). The mean BCVAs of two groups were 0.16 ± 0.43 (range, 0.00-3.10) logMAR and 0.17 ± 0.42 (range, 0.00-3.10) logMAR, respectively. There were no statistically significant differences between Groups 1 and 2 regarding gender or clinical characteristics (p > 0.05). No significant differences were detected in pre- or post-dilatation values between two groups (p = 0.470, p = 0.998).

CONCLUSIONS

As a result, anterior chamber flare values in uveitis patients do not differ significantly between 1% tropicamide and 1% cyclopentolate hydrochloride, and both agents can be safely used for dilatation during examination of patients with uveitis.

Changes in intraocular pressure and aqueous flare in eyes with multiple evanescent white dot syndrome

PURPOSE

To study the changes in intraocular pressure (IOP) and aqueous flare in eyes with multiple evanescent white dot syndrome (MEWDS) during the disease course.

STUDY DESIGN

Retrospective observational study.

METHODS

Twenty-one patients with unilateral MEWDS were retrospectively evaluated. IOP values were compared between the affected and fellow eyes 2 weeks, 1 month, and 3 months following disease onset in 17 patients, and within 7 days from disease onset in 11 patients. Aqueous flare values measured using a laser flare-cell meter in ten eyes between 1 weeks and 1 month from disease onset were compared between the affected and fellow eyes.

RESULTS

IOP values were significantly lower in the affected eyes than in the fellow eyes at both 2 weeks (P=0.002) and 1 month from disease onset (P=0.02). However, IOP values of affected eyes did not show significant differences from the fellow eyes within 7 days ((P=0.11) and 3 months of onset (P=0.30). Aqueous flare values were significantly increased in the affected eyes compared to those in the fellow eyes (P=0.010) and significantly correlated with IOP values (r=-0.67, P=0.035).

CONCLUSION

IOP values mildly decreased in association with aqueous flare values in the acute phase in eyes with MEWDS.

Correlation between anterior chamber flare changes and diabetic macular edema after intravitreal injection of ranibizumab and aflibercept

PURPOSE

To evaluate aqueous flare change patterns following anti-vascular endothelial growth factor therapy for diabetic macular edema (DME) and investigate the relationship between changes in flare values and central macular thickness (CMT).

STUDY DESIGN

Retrospective, interventional case series METHODS: A total of 84 eyes of 62 patients with DME received either intravitreal ranibizumab (IVR; n = 62) or aflibercept (IVA; n = 22). A laser flare photometer (Kowa FM500, Kowa Company, Ltd) was used to measure flare values, and CMT was assessed using optical coherence tomography. Flare values and CMT were measured prior to injection (baseline) and at, 1, 7 and 14 days after injection.

RESULTS

Flare values in the IVR group decreased significantly at day 14 (P = 0.001), whereas the IVA group showed a significant increase in flare values at day 1 (P < 0.001). In the IVA group, the baseline flare values were significantly higher in the CMT reduction group than in the non-CMT reduction group (P = 0.035). There was no correlation between changes in flare values and CMT either in the IVA or IVR group.

CONCLUSIONS

Flare value changes in patients treated with IVR decreased at day 14 post-injection. This may indicate when the most anti-inflammatory effect was obtained. There was no correlation between changes in flare values and CMT either in the IVA or IVR group; nevertheless, our research suggests that the baseline flare value is a predictive factor for the efficacy of IVA in DME.

Identification of Underlying Inflammation in Vogt-Koyanagi-Harada Disease with Sunset Glow Fundus by Multiple Analyses

Purpose

To evaluate underlying subclinical ocular inflammation in Vogt-Koyanagi-Harada (VKH) disease with sunset glow fundus (SGF) by multiple analyses.

Study Design

Retrospective observational study.

Methods

Clinical records of 34 eyes of 17 VKH patients with SGF in whom laser flare photometry (LFP), enhanced depth imaging optical coherence tomography (EDI-OCT), and indocyanine green angiography (ICGA) were performed on the same day were reviewed. The mean age was 57.3 ± 16.3 years, and the mean duration from the initial onset of uveitis was 47.1 ± 22.1 months. Flare counts, ICGA scores, and subfoveal choroidal thickness (SFCT) were compared between eyes.

Results

Although clinical ocular inflammation was observed only in 4 eyes (11.8%), inflammatory signs were observed in 23 out of 34 eyes by LFP (67.6%), in 27 eyes by ICGA (79.4%), and in 10 eyes by SFCT (29.4%). Active inflammatory signs detected by ICGA were observed in 77.8% by LFP and in 25.9% by SFCT. The strength of agreement (Cohen's kappa coefficient) between positive ICGA score and positive flare score was 0.406 (95% CI: 0.076-0.7359, P < 0.01), but there was no association between positive ICGA score and increased SFCT. In addition, positive flare count was the significant prognostic factor of positive ICGA score with odds ratio 11.7.

Conclusions

Subclinical ocular inflammation signs were detected in most VKH patients with SGF by ICGA and a substantial proportion of which were also detected by LFP, whereas SFCT was less sensitive to detect subclinical inflammation.

Effect of Tropicamide on Laser Flare Meter Measurements in Patients with Pseudoexfoliation

PURPOSE

To investigate the effect of 1% tropicamide on anterior chamber aqueous flare (ACAF) measurements acquired with laser flare meter in patients with pseudoexfoliation.

METHODS

Thirty-three eyes of 33 patients with pseudoexfoliation were enrolled. Patients with the history of other ocular diseases, intraocular surgeries, and the presence of severe posterior synechia were excluded. Besides routine ophthalmological examination, ACAF levels were measured by laser flare meter device (Kowa FM 600) before and after instillation of 1% tropicamide.

RESULTS

The mean age of 33 patients was 67.3±7.1 (53-85) years. Patients had a mean best corrected visual acuity of 0.25±0.41 (1.80-0.00) logMAR, cup-to-disc ratio of 0.45±0.22 (0.2-1), and IOP of 15.33±2.82 (9-20) mmHg. Although the mean ACAF value increased from 14.68±8.40 (3.4-40.4) photon/ms predilation to 15.41±10.74 (3.8-46.8) photon/ms post-dilation, the difference was not statistically significant (p=0.835).

CONCLUSIONS

ACAF values in patients with pseudoexfoliation did not significantly differ after instillation of 1% tropicamide.

Instrument-based Tests for Measuring Anterior Chamber Cells in Uveitis: A Systematic Review

Purpose

New instrument-based techniques for anterior chamber (AC) cell counting can offer automation and objectivity above clinician assessment. This review aims to identify such instruments and its correlation with clinician estimates.

Methods

Using standard systematic review methodology, we identified and tabulated the outcomes of studies reporting reliability and correlation between instrument-based measurements and clinician AC cell grading.

Results

From 3470 studies, 6 reported correlation between an instrument-based AC cell count to clinician grading. The two instruments were optical coherence tomography (OCT) and laser flare-cell photometry (LFCP). Correlation between clinician grading and LFCP was 0.66–0.87 and 0.06–0.97 between clinician grading and OCT. OCT volume scans demonstrated correlation between 0.75 and 0.78. Line scans in the middle AC demonstrated higher correlation (0.73–0.97) than in the inferior AC (0.06–0.56).

Conclusion

AC cell count by OCT and LFP can achieve high levels of correlation with clinician grading, whilst offering additional advantages of speed, automation, and objectivity.

Breakdown of the blood-eye barrier in choroidal melanoma after proton beam radiotherapy

PURPOSE

Irradiation of choroidal melanoma is a safe and globe preserving procedure. Chronic inflammatory processes and ischemia are the main reasons for secondary enucleation in the long run. The aim of this study was to determine whether intraocular inflammation and especially inflammatory response after proton beam therapy (PBT) is related to primary tumor characteristics such as height, tumor volume, and initial flare values.

METHODS

Twenty-six patients treated for uveal melanoma using PBT were included. All patients were examined for signs of inflammation using laser flare photometry (LFP). Each examination included assessment of the melanoma and fellow eye (which acted as the control) and imaging of the melanoma.

RESULTS

Significant differences of flare values between melanoma eyes and control group were found both at baseline (median 17.65 ph/ms (min 4, max 37.10), 7.45 ph/ms (min 0.80, max 16.40), respectively) and during follow-up (median 21.45 ph/ms (min 4.5, max 70.90); 6.05 ph/ms (min 2.40, max 16.40), respectively) (p < 0.001, Wilcoxon test). Flare values in melanoma eyes increased significantly after PBT (p = 0.005, Wilcoxon test) and after a follow-up of 94 days (median, 7-420 days). Flare values of the control group did not change (p = 0.946, Wilcoxon test). The increase of flare values correlated significantly with maximum tumor height and volume (Spearman-Rho 0.633, p = 0.001 and 0.519, p = 0.007, respectively).

CONCLUSION

LFP has proven to show significantly higher flare values in melanoma eyes as compared with the control group and provides data on the course of the inflammatory response after treatment. It may ease treatment planning both at baseline and during follow-up.

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.

Comparison of postoperative ciliary body changes associated with the use of 23-gauge and 20-gauge system for pars plana vitrectomy

Background

To compare the ciliary body changes associated with the use of 23-gauge (23G) and 20-gauge (20G) systems for pars plana vitrectomy.

Methods

A total of 60 patients (60 eyes) with idiopathic epiretinal membrane who were scheduled for surgical treatment were selected and randomly assigned to 20G group or 23G group. Time required for incision making, vitrectomy, and incision closure was compared between the two groups. Changes in ciliary body were evaluated by ultrasound microscopy (UBM). Anterior chamber inflammation was assessed with laser flare meter instrument.

Results

Incision-making time (4.5 ± 0.9 min) and incision-closure time (2.8 ± 0.7 min) in the 23G group were significantly shorter than those in the 20G group (10.1 ± 1.5 min and 11.3 ± 2.2 min, respectively). No significant intergroup difference was observed with respect to time required for vitrectomy (21.6 ± 3.3 min and 20.7 ± 3.2 min, respectively). Ciliary body thickness in the 23G group recovered back to preoperative levels after 4 weeks, as against 8 weeks in the 20G group. Postoperative ciliary body thickness in the 20G group was significantly higher than that in the 23G group (p < 0.05). The aqueous protein concentration in 23G group recovered back to preoperative levels after 2 weeks, as against 4 weeks in the 20G group. Postoperative aqueous protein concentration in the 20G group was significantly higher than that in the 23G group (p < 0.05).

Conclusions

The use of 23G system was associated with significantly milder injury to the ciliary body as compared to that associated with the use of 20G system.

Trial registration

The study was retrospectively registered on Chinese Clinical Trial Registry. The clinical study registration number was ChiCTR-INR-17011082. Date of registration: 2017-04-07.