Measurement of protein concentration of aqueous humour in vivo: correlation between laser flare measurements and chemical protein determination

The Value of Laser Flare Photometry as a Monitoring Tool for Uveitis

Laser flare (LF) photometry (P) is used to quantify the protein concentration in the aqueous humor, and therefore assess the blood-aqueous humor barrier. LFP is more reliable than the clinical assessment of the Tyndall effect, and is thus especially useful in the follow-up of uveitis patients. In active uveitis, LFP correlates well with the anterior chamber cell grading. Various studies have shown that high LF values are associated with an increased risk of uveitic complications, such as macular edema, glaucoma, and posterior synechiae. LFP can also be used to assess the response to anti-inflammatory treatments as well as the optimal timing and selection of the surgical technique for intraocular surgeries.

The Correlation of Inflammation and Microvascular Changes with Diabetic Retinal Neurodegeneration

Purpose: To evaluate the effect of aqueous flare intensity as a measurement of inflammation and microvascular changes on retinal neurodegeneration in diabetic eyes.Materials and Methods: In cross-sectional study diabetic patients were assigned into 2 groups according to the presence of retinopathy: patients with nonproliferative diabetic retinopathy (group 1) and diabetic patients without clinically overt retinopathy (group 2). As a control group (group 3), age-matched healthy controls were included in the study. All subjects underwent visual acuity measurement, slit-lamp examination, ophthalmoscopy, spectral-domain optic coherence tomography (SD-OCT), optic coherence tomography angiography (OCTA), and laser flare-cell meter (LFCM).Results: The study enrolled 99 eyes of 99 patients in group 1; 99 eyes of 99 patients in group 2, and 50 eyes of 50 age-matched healthy controls in group 3. The eyes in group 1 had higher flare intensity, decreased ganglion cell layer (GCL) thickness, enlarged foveal avascular zone (FAZ) area, and enlarged capillary non-flow area compared to those in group 2 (p < .005). In group 1, decreased GCL thickness was statistically significantly correlated with increased aqueous flare intensity, enlarged FAZ area, and enlarged capillary non-flow area (p < .005).Conclusion: The results demonstrated a correlation of the retinal neurodegeneration with the aqueous flare levels and macular ischemia indices in the early stages of diabetic retinopathy. This finding supports the role of inflammation in the pathogenesis of diabetic retinal neuropathy.

Pre-Gestational Diabetes and Pregnancy Outcomes

INTRODUCTION

Pre-gestational, type 1 and type 2 diabetes are associated with adverse neonatal outcomes and increased rates of emergency caesarean sections.

METHODS

We studied pregnancy outcomes associated with pre-gestational diabetes in 174 women who attended the National Maternity Hospital in Dublin, Ireland, between 2015 and 2017.

RESULTS

Fifty women (28.6%) had type 2 diabetes mellitus, and 124 women (71.4%) had type 1 diabetes mellitus. Women with type 2 diabetes mellitus were older (36 vs. 34 years, p 0.02) and had a higher BMI (32.6 vs. 26.2 kg/m2, p 0.00). Duration of diabetes mellitus in type 1 and type 2 was 15.7 and 5.7 years, respectively, and mean HbA1c in type 2 diabetes mellitus at booking was 44.5 mmol/mol (6.2%) and in type 1 diabetes mellitus was 56.3 mmol/mol (7.3%). Forty women (32%) with type 1 diabetes mellitus used continuous subcutaneous insulin infusion. In our cohort, 45.4% had a caesarean delivery. Offspring of patients with multiple dose injections were lighter (3.58 kg) than infants of continuous subcutaneous insulin infusion-treated patients (3.75 kg). More emergency caesarean sections were observed in the continuous subcutaneous insulin infusion group than in the group treated with multiple dose injections (37.5% vs. 28.5%), while the elective caesarean section rate was higher in the multiple dose injection group (17.8% vs. 12.5%). Women treated with continuous subcutaneous insulin infusion had a higher rate of miscarriage (25% vs. 19%) with more congenital malformations (10% vs. 2.3%).

CONCLUSIONS

Women in our study with pre-gestational diabetes were overweight, were older and had long-standing diabetes mellitus. Our patients with type 2 diabetes had a higher BMI, were older, had a shorter duration of diabetes mellitus and had better diabetes control compared to women with type 1 diabetes. Women treated with continuous subcutaneous insulin infusion had a higher rate of miscarriage with more congenital malformations. The initial inadequate diabetes control was significantly improved during pregnancy.

Measuring Anterior Chamber Inflammation After Cataract Surgery: A Review of the Literature Focusing on the Correlation with Cystoid Macular Edema

Cystoid macular edema (CME) is an infrequent, though potentially visually impairing, complication after uneventful cataract surgery. Rupture of the blood-aqueous barrier, with leakage of serum proteins into the aqueous humour, is the main pathogenic factor. However, only a few studies investigated the potential correlation between anterior chamber (AC) inflammation and the risk of cystoid macular changes occurring after surgery. This review aims to identify evidence of a correlation between AC inflammation and the risk of pseudophakic CME. One hundred eighty-seven prospective trials investigating AC inflammation after uncomplicated cataract surgery were identified. Methods of analysis of AC inflammation and the frequency of macular changes were recorded. In the majority (51%) of the studies, inflammation was assessed by clinical grading, followed by laser flare and cell photometry (LFCP) (42%) and aqueous humour sample (4%). Few studies (4%) adopted a combined LFCP and aqueous sample or clinical grading analysis. Sixteen (9%) studies investigated AC inflammation and macular changes by OCT (7%) or fluorescein angiography (2%). Correlation between the amount of postoperative AC inflammation and frequency of CME was documented in 7 studies, not confirmed in 2 studies, and not examined in the other 7. LFCP, more than the other methods of analysis, correlated with the frequency of CME postoperatively. Investigation of the relationship between AC inflammation and the risk of CME changes requires the adoption of quantitative methods of analysis of the inflammatory response after surgery. For this purpose, due to the low level of inflammation in the AC after uncomplicated cataract surgery, LFCP, more than subjective clinical grading, seems a more sensitive and reproducible method of measurement. Inflammation assessment after cataract surgery has a potential role in predicting the risk of CME development and may help to titrate the duration and intensity of treatment in relation to the surgical inflammatory response.

Instrument-based tests for quantifying aqueous humour protein levels in uveitis: a systematic review protocol

BACKGROUND

Inflammation in anterior uveitis is characterised by breakdown of the blood-ocular barrier, which allows leakage of blood constituents of higher molecular weight into the aqueous humour. In routine clinical care, increase in aqueous protein levels can be observed at the slit lamp as 'flare' and the severity can be graded using various clinical grading systems, of which the Standardization of Uveitis Nomenclature (SUN) grading system is most commonly used. Alternative instrument-based technologies are available, which can detect aqueous protein levels in an objective and quantifiable way. This review will identify instruments capable of measuring anterior chamber inflammation in this way, their level of reliability, and how well the measurements correlate with clinical grading and/or actual aqueous protein concentration.

METHODS

Standard systematic review methodology will be used to identify, select and extract data from studies that report the use of any instrument-based technology in the assessment of aqueous protein levels. Searches will be conducted through bibliographic databases (MEDLINE, EMBASE and Cochrane Library), clinical trial registries and the grey literature. No restrictions will be placed on language or year of publication. The outcomes of interest are the level of correlation between identified instrument-based test measurements, clinical grading and/or actual aqueous protein concentration, as well as the reliability of each index test identified. Study quality assessment will be based on QUADAS2. Correlation and reliability outcomes will be pooled and meta-analysed if appropriate.

DISCUSSION

The assessment of inflammation in anterior chamber protein levels currently relies on crude and subjective clinical examination. The findings of this review will identify non-invasive technologies which show good correlation with actual protein concentration, which could be used in routine clinical practice for objective monitoring of AC inflammation.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017084167. Study screening stage has just been completed.

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.

Comparative Analysis of Anterior Chamber Flare Grading between Clinicians with Different Levels of Experience and Semi-automated Laser Flare Photometry

PURPOSE

To assess correlation for anterior chamber flare grading between clinicians with different levels of experience and with semi-automated flare reading in a cohort of patients with heterogeneous uveitic entities.

METHODS

Fifty-nine observations from 36 patients were recorded and analyzed for statistical association. In each patient, flare was assessed objectively using the Kowa FM-700 laser flare photometer, and subjective masked grading by two clinicians was performed.

RESULTS

The study demonstrated disparity in flare readings between clinical graders with one step disagreement in clinical grading in 26 (44.06%) eyes (p < 0.001) and concordance between the flare readings by experienced grader and flare photometry. After review of semi-automated flare readings, management was changed in 11% of the patients.

CONCLUSION

Laser flare photometry can be a valuable tool to remove the observer bias in grading flare for selected cohort of uveitis patients. It can be further applied to titrate therapy in intraocular inflammation.

Intracameral triamcinolone acetonide in glaucoma surgery: a prospective randomized controlled trial

PURPOSE

To evaluate the efficacy and safety of intracameral triamcinolone acetonide (TA) in glaucoma surgery.

DESIGN

Prospective randomized clinical trial.

METHODS

SETTING

Institutional-Wills Eye Hospital.

STUDY POPULATION

Patients undergoing trabeculectomy (with or without cataract surgery) or tube shunt surgery.

INTERVENTION

Patients were randomized to receive intracameral TA or balanced salt solution at the end of surgery. Follow-up time was 6 months.

MAIN OUTCOME MEASURES

Intraocular pressure, visual acuity, inflammation measured by slit-lamp examination and laser flare meter, cataract grading, bleb appearance, dry eye scores, use of supplemental medical therapy, surgical success, and rate of complications.

RESULTS

Seventy-seven patients were enrolled in the study, including 37 in the TA group and 40 in the control group. There were no significant differences in success rates between the 2 groups (P=.60). Intraocular pressure and medication use were similar between the groups for each follow-up visit. Dry eye scores were lower in the TA group at month 1 (P=.042), while flare scores were higher in the TA group on day 1 (P=.015) but lower at month 1 (P=.044). The complication rates were higher in the TA group on day 1 (P=.04). All other outcome measures were similar for both groups.

CONCLUSIONS

Intracameral TA did not affect the success rates or change the complication rates of glaucoma surgery.

Role of inflammation in previously untreated macular edema with branch retinal vein occlusion

BACKGROUND

The association of inflammatory factors and the aqueous flare value with macular edema in branch retinal vein occlusion (BRVO) patients remains unclear. The relationship between the aqueous flare value and the vitreous fluid levels of vascular endothelial growth factor (VEGF), interleukin (IL)-6, monocyte chemotactic protein (MCP)-1, soluble intercellular adhesion molecule 1 (sICAM-1), and soluble VEGF receptor-2 (sVEGFR-2) was evaluated to investigate the role of inflammation in BRVO associated with macular edema. Aqueous flare values and the vitreous levels of VEGF, IL-6, MCP-1, sICAM-1, and sVEGFR-2 were compared between previously untreated patients with BRVO and patients with macular hole (MH).

METHODS

Vitreous samples were obtained from 45 patients during vitreoretinal surgery (28 patients with BRVO and 17 with MH), and the levels of VEGF, IL-6, MCP-1, sICAM-1, and sVEGFR-2 were measured by enzyme-linked immunosorbent assay. Retinal ischemia was evaluated by measuring the area of capillary non-perfusion using fluorescein angiography and the Scion Image program. Aqueous flare values were measured with a laser flare meter and macular edema was examined by optical coherence tomography.

RESULTS

The median aqueous flare value was significantly higher in the BRVO group (12.1 photon counts/ms) than in the MH group (4.5 photon counts/ms, P < 0.001). There were significant correlations between the aqueous flare value and the vitreous levels of VEGF, IL-6, MCP-1, and sICAM-1 in the BRVO group (ρ = 0.54, P = 0.005; ρ = 0.56, P = 0.004; ρ = 0.52, P = 0.006; and ρ = 0.47, P = 0.015, respectively). The aqueous flare value was also significantly correlated with the foveal thickness in the BRVO group (ρ = 0.40, P = 0.037).

CONCLUSIONS

Inflammation may induce an increase of vascular permeability and disrupt the blood-aqueous barrier via release of inflammatory factors (VEGF, IL-6, MCP-1, and sICAM-1) in BRVO patients with macular edema.

Calcification of a hydrophilic acrylic intraocular lens: clinicopathological report

A 72-year-old man who had phacoemulsification with implantation of an Akreos Adapt Advanced Optics (AO) IOL in the left eye complained of blurring vision 4 months postoperatively. Multiple fine white granules were found within the IOL. Intraocular lens exchange was performed at 7 months, and the explanted IOL was sent for histopathological analysis. Diffuse fine white granules were seen within the explanted IOL material just beneath the surface; they were stained positive by alizarin red and the von Kossa method. Scanning electron microscopy confirmed the presence of calcium deposits in the IOL material. Blood and aqueous were drawn from the patient for biochemical analysis, and the results were normal. We believe this is the first clinicopathological report of calcification of the Akreos Adapt AO IOL.

Aqueous flare and cells in Fuchs syndrome

PURPOSE

To quantitatively evaluate aqueous flare and cells in patients with Fuchs syndrome.

METHODS

The medical records of 40 patients (47 eyes) diagnosed with Fuchs syndrome between February 2006 and January 2007 at the Uveitis Study Center of Sun Yat-sen University were retrospectively reviewed. Aqueous flare and cells were clinically evaluated and quantified with laser flare-cell meter. Statistical analysis was performed to investigate the relationship between flare values and cell counts, and clinical parameters including patients' age, sex, duration of disease, best-corrected visual acuity, keratic precipitate, iris depigmentation, intraocular pressure, and posterior subcapsular lens opacities.

RESULTS

Aqueous flare values (photon counts/ms) were significantly higher in Fuchs syndrome (9.40+/-5.85) than in normal controls (5.77+/-1.89, P=0.000). Aqueous cell counts (cells/0.5 mm(3)) were also significantly higher in Fuchs syndrome (5.09+/-4.84) than in normal controls (1.14+/-1.03, P=0.000). The flare values were positively correlated with the cell counts (r=0.331, P=0.001). Both flare values and cell counts were higher in eyes with keratic precipitates scored 2+ or 3+ as compared to those with a 1+ score. Higher flare values and cell counts were also observed in eyes with a 2+ or 3+ iris depigmentation score as compared to those with a 1+ score. No difference was found between flare values and cell counts and other parameters.

CONCLUSION

Breakdown of blood-aqueous barriers and increased cell counts are present in the affected eyes in patients with Fuchs syndrome. These changes are positively associated with the degree of keratic precipitates and iris depigmentation.

Clinical evaluation using Custom Control Software technology in coaxial phacoemulsification

PURPOSE

The aim of this study was to evaluate the clinical outcomes of the Custom Control Software technology in coaxial phacoemulsification.

METHODS

This prospective, randomized, double-masked clinical trial was conducted at the Eye Center, Affiliated Second Hospital, College of Medicine, Zhejiang University. The patients were grouped according to nuclear sclerosis and randomly assigned to undergo conventional phacoemulsification or phacoemulsification using Millennium Custom Control Software (CCS). All surgeries were performed by a single surgeon. The phaco time and average power of phacoemulsification were recorded and then calculated as absolute phaco time (APT). Visual acuity, pachymetry, endothelial cell density and anterior chamber flare count of both groups were noted at preoperatively day 1 and 3 months after surgery.

RESULTS

The APT of the CCS group was statistically lower than Conventional group in grades II, III and IV (P < 0.05) nuclear sclerosis, but the two groups had no statistically significant differences in the grade I group. At day 1 post surgery, there were significant differences in the thickened pachymetry (P = 0.047) and anterior chamber flare counts (P = 0.008) between two groups. At 3 months post surgery, the endothelial cell loss ratio showed statistical difference (P = 0.032) between two groups.

CONCLUSIONS

Using CCS technology in coaxial phacoemulsification can provide lower APT and better power efficiency. This new power modulation may make the surgery safer and more effective than Conventional phacoemulsification.

Comparison of topical 0.7% dexamethasone-cyclodextrin with 0.1% dexamethasone sodium phosphate for postcataract inflammation

BACKGROUND

To compare 0.7% dexamethasone-cyclodextrin aqueous eye drop solution applied once daily with 0.1% dexamethasone sodium phosphate eye drops applied three times a day for the control of postoperative inflammation after cataract surgery.

METHODS

Twenty cataract patients who underwent phacoemulsification and intraocular lens implantation were randomly divided into two postoperative treatment groups. Postoperative medication in group I included 0.1% dexamethasone sodium phosphate eye drops three times daily and in group II 0.7% dexamethasone-cyclodextrin eye drop solution once daily. Testing of visual acuity, biomicroscopic examination, applanation tonometry and laser flare cell meter (LFCM) examination were carried out before operation and days 1, 3, 7 and 21 after surgery.

RESULTS

Preoperative and postoperative visual acuity, aqueous flare and cells in biomicroscopic examination, and the mean intraocular pressure did not show any statistically significant differences between the treatment groups. LFCM examination showed that the mean postoperative photon count values (P=0.032) and the median cell count values on the 1st (P=0.014), 3rd (P=0.031), 7th (P=0.034), and 21st (P=0.0097) postoperative days in group I were more elevated than in group II.

CONCLUSIONS

0.7% dexamethasone-cyclodextrin eye drops applied once daily is a more effective postoperative anti-inflammatory medication than 0.1% dexamethasone sodium phosphate applied three times a day. In both groups, 3 weeks after the operation the mean visual acuity was normal and intraocular pressure significantly lower than before operation. The use of 0.7% dexamethasone-cyclodextrin eye drops may be useful especially in elderly people who cannot apply themselves the eye drops onto the eye.

Disorders of the blood-aqueous barrier after phacoemulsification in diabetic patients

PURPOSE

To evaluate the function of the blood-aqueous barrier after phacoemulsification with implantation of a foldable intraocular lens (IOL) in diabetic patients.

METHODS

All patients were enrolled from those scheduled for phacoemulsification with intraocular lens implantation in Zhongshan Ophthalmic Center Guangzhou from March 2002 to June 2002. The classification on diabetic retinopathy (DR) was based on the fundus examination after cataract surgery. The blood-aqueous barrier function was examined using the laser flare cell meter (Kowa FC-2000) preoperatively and on postoperative days 1, 7, 30, and 90 by an independent examiner who was masked to the DR classification. Patients were operated by one experienced surgeon as per standard clinical protocol and were provided the same postoperative medical care. A linear regression and Wilcoxon test were used for the analysis.

RESULTS

A total of 112 patients were divided into three groups: patients without diabetic mellitus as normal control (n=56), diabetic patients without diabetic retinopathy (n=2), with nonproliferation diabetic retinopathy (NPDR) (n=37), and diabetic patients with proliferation diabetic retinopathy (PDR) (n=17). All patients were examined and successfully followed up for 3 months after cataract surgery. Aqueous flare mean photon counts in PDR, NPDR, and control eyes were 8.94+/-0.57, 7.03+/-0.27, and 6.94+/-0.34 before surgery and increased to 32.42+/-0.67, 26.07+/-0.83, 26.27+/-1.37 on the first day after surgery (P<0.05), then decreased to 19.86+/-0.78, 14.08+/-0.54 and 13.96+/-1.05 at 7 days after surgery (P<0.05), 13.24+/-0.29, 9.86+/-0.33, and 9.07+/-0.43 at 30 days after surgery (P<0.05); eventually, the counting decreased to 11.25+/-0.31, 7.24+/-0.67, and 7.16+/-0.27 at 90 days after surgery (P<0.05). Linear regression model suggested that other potential variables, such as age, sex, eye (left/right), phaco time, phaco energy, and hypertension were not related to the outcome. For patients without diabetes mellitus and diabetic patients with NPDR, highly statistically significant differences (P<0.05) were found between preoperative flare value and those measured on days 1, 7, and 30 after surgery, but no statistically significant differences (P>0.05) were found between the preoperative flare value and those measured on postoperative days 90. However, patients with PDR still had a higher flare value even on postoperative day 90. The patients with intraoperative iris prolapse had a higher flare value between days 1 and 7 postoperatively.

CONCLUSION

Phacoemulsification with a foldable intraocular lens implantation affects the blood-aqueous barrier more severely in diabetic patients with PDR than patients with NPDR and nondiabetic patients.

Evaluation of the blood–aqueous barrier by laser flare cell photometry following retinal cryocoagulation

PURPOSE

To evaluate the influence of peripheral 360 degrees retinal cryocoagulation on the blood-aqueous barrier of patients with retinal vascular disorders.

METHODS

The aqueous of 50 eyes of 50 patients with diabetic retinopathy or central vein occlusion was measured by laser flare photometry (FC-2000, Kowa) before peripheral 360 degrees retinal cryocoagulation and 1 day, 1 week, and 1 month thereafter.

RESULTS

Mean aqueous flare values before treatment were 15.7 (+/-8.2) photon counts/ms; mean cell count was 9.8 (+/-14.8) cells/0.5 mm(3). One day after retinal cryocoagulation flare values had increased statistically significantly to a mean of 39.2 (+/-85.8) photon counts/ms, while the increase in mean cell number to 15.0 (+/-37.2) cells/0.5 mm(3) did not reach statistical significance. One week following treatment, mean flare values had dropped to 30.9 (+/-49.6) photon counts/ms and were no longer significantly elevated compared with baseline, while the mean cell count of 11.1 (+/-27.0) cells/0.5 mm(3) was now statistically significantly elevated compared with baseline. One month after treatment the flare values had decreased to a mean of 19.7 (+/-12.0) photon counts/ms, and mean cell count had decreased to 8.1 (+/-10.4) cells/0.5 mm(3); at this point neither parameter showed a statistically significant difference from baseline values.

CONCLUSION

Peripheral 360 degrees retinocryocoagulation does not lead to permanent disturbance of the blood-aqueous barrier.

Prevalence of subclinical anterior uveitis in adult patients with inflammatory bowel disease

AIM

To assess the prevalence of subclinical anterior uveitis in adult patients with inflammatory bowel disease.

METHODS

In 179 consecutive patients (96 with Crohn's disease, 55 with ulcerative colitis, and 28 with inflammatory bowel disease of undetermined nature) without previous or concurrent ocular complaints, quantitative flare measurements were obtained with the Kowa FC laser flare to detect the presence of subclinical uveitis.

RESULTS

The mean flare value was 3.9 (SD 1.1) ph/ms in patients younger than 30 years of age, rising to 5.8 (2.5) ph/ms in those over 60 years of age. No measurement performed in this patient population fell outside the mean observed value plus or minus SD of the normal controls within the same age category.

CONCLUSION

In an adult population of 179 consecutive patients with inflammatory bowel disease the presence of a form of subclinical uveitis, as described by Hofley et al in a group of juvenile patients, is highly unlikely.