A review of functional slit lamp biomicroscopy

Functional slit lamp biomicroscopy(FSLB)is a novel device which consists of a traditional slit-lamp and a digital camera.It can quantitatively assess vessel diameter,blood flow velocity,and blood flow rate and can create noninvasive microvascular perfusion maps(nMPMs).At present,FSLB is mainly used in contact lens(CL)and dry eye disease(DED)studies to advance our understanding of ocular surface microcirculation.FSLB-derived blood flow and vessel density measures are significantly altered in CL wearers and DED patients compared to normal people.These subtle changes in the ocular surface microcirculation may contribute to the monitoring of potential diseases of the body and provide a new way to diagnose dry eye disease.Therefore,this may also indicate that FSLB can be more widely applied in the study of other diseases to reveal the relationship between changes in ocular surface microcirculation and systemic diseases.The purpose of this paper is to summarize the functions of FSLB and the related studies especially in CL and DED.

Quantitative analysis of conjunctival microvasculature imaged using optical coherence tomography angiography

Background:The goal was to quantitatively analyze the bulbar conjunctival microvascular density using optical coherence tomography angiography(OCTA)and compare it to the vessel density using functional slit-lamp biomicroscopy(FSLB).Methods:Temporal bulbar conjunctiva of 20 eyes(10 healthy subjects)was imaged using both OCTA and FSLB.Image processing was performed including equalization,de-noising,thresholding,and skeletonization.The vessel density was measured by fractal analysis(box counting,Dbox)and pixel counting(%).Results:Vessel density(Dbox)of the bulbar conjunctiva obtained using OCTA was 1.28±0.01 Dbox,which was significantly lower than the result(1.32±0.01 Dbox,P<0.001)obtained using FSLB.Furthermore,the vessel density(%)obtained using OCTA was 3.31±0.12%,which was also significantly lower than the result(3.69±0.16%,P<0.001)obtained using FSLB.No significant correlations(r ranged from 0.21 to 0.32,P>0.05)between both instruments were found in both vessel density methods(Dbox and percentage).However,in each of the devices,vessel density in Dbox was significantly correlated with the vessel density in percentage(r=1.0 for FSLB and r=0.98 for OCTA,both P<0.001).Conclusion:This study demonstrated that the vessel density of the bulbar conjunctiva obtained using OCTA can be quantified,and the results were not compatible with that obtained using slit-lamp biomicroscopy photography.