Laboratory investigations in uveitis: current practice and future directions

Diagnosis and management of uveitis always remains a challenge to the treating ophthalmologists. Rapid diagnosis and timely initiation of appropriate, effective treatment in uveitis are the critical determinants that lead to good visual outcome and reduce the risk of ocular morbidity. In the last decade, significant progress has been made in molecular diagnostic modalities and in development of newer diagnostic tools, which included serological tests and imaging techniques. However, a tailored approach to laboratory investigations based on meticulous history and comprehensive ocular evaluation has been propounded as the gold standard for successful management of an uveitic entity. In this article, we review the laboratory diagnostic tests in uveitis as well as recent technological advances in laboratory science, which may be the future direction for diagnosis of uveitis.     

Population screening for glaucoma in UK: current recommendations and future directions

Effective population screening for glaucoma would enable earlier diagnosis and prevention of irreversible vision loss. The UK National Screening Committee (NSC) recently published a review that examined the viability, effectiveness and appropriateness of a population-based screening programme for primary open-angle glaucoma (POAG). In our article, we summarise the results of the review and discuss some future directions that may enable effective population screening for glaucoma in the future. Two key questions were addressed by the UK NSC review; is there a valid, accurate screening test for POAG, and does evidence exist that screening reduces morbidity from POAG compared with standard care. Six new studies were identified since the previous 2015 review. The review concluded that screening for glaucoma in adults is not recommended because there is no clear evidence for a sufficiently accurate screening test or for better outcomes with screening compared to current care. The next UK NSC review is due to be conducted in 2023. One challenge for POAG screening is that the relatively low disease prevalence results in too many false-positive referrals, even with an accurate test. In the future, targeted screening of a population subset with a higher prevalence of glaucoma may be effective. Recent developments in POAG polygenic risk prediction and deep learning image analysis offer potential avenues to identifying glaucoma-enriched sub-populations. Until such time, opportunistic case finding through General Ophthalmic Services remains the primary route for identification of glaucoma in the UK and greater public awareness of the service would be of benefit.Subject terms: Optic nerve diseases, Predictive markers     

Validity of percentage tissue altered as a screening formula for post laser-assisted in-situ keratomileusis ectasia in Indian eyes

Purpose:To calculate a modified percentage tissue altered (mPTA) in post laser-assisted in-situ keratomileusis (LASIK) eyes and to validate its role as an independent factor to evaluate ectasia in the Indian population.Methods:A total of 333 consecutive eyes with normal preoperative corneal topography by combined placido and scheimpflug imaging-based topography system (SIRIUS) who underwent LASIK using a microkeratome between 2011 and 2014 at a tertiary level teaching hospital in south India, were retrospectively analyzed. Preoperatively patient''s refraction, flap thickness (FT), ablation depth (AD), residual stromal bed (RSB), and thinnest corneal thickness (TCT) were recorded. The formula used was mPTA = (FT + AD)/TCT. mPTA was grouped into <0.4 (low risk), 0.40 - 0.45 (moderate risk), and >0.45 (high risk). All patients were called for follow-up and underwent a topography to look for ectasia.Results:In total 60.1%, 29.1%, and 10.8% patients had mPTA of <0.4, 0.40 - 0.45 and >0.45, respectively. However, after a minimum follow-up of 2 years, none of the patients had any sign of ectasia.Conclusion:Careful selection of patients is mandatory before proceeding for LASIK. Factors like corneal thickness, RSB, degree of myopia, and AD are more important. The role of mPTA >0.4 as an independent risk factor for post LASIK ectasia is questionable in Indian eyes. Other factors or a modified formula suitable for Indian eyes needs to be investigated. A larger follow-up period is also required as ectasia has been known to develop even after 2 years.     

Endothelial keratoplasty: historical perspectives, current techniques, future directions

Endothelial keratoplasty (EK) has recently emerged as an alternative to penetrating keratoplasty (PK) for patients with endothelial diseases, including Fuchs’ endothelial dystrophy, pseudophakic bullous keratopathy, and corneal graft failure. EK provides distinct advantages over PK, in that it is a less invasive procedure and leads to more rapid recovery of vision. Additionally, this procedure does not require long-term corneal sutures, eliminating problems with suture breakage, suture abscesses, astigmatism, and wound dehiscence. Disadvantages of EK include the need for specially prepared donor tissue and additional surgeon training or experience. In this review we discuss the history of EK, recent advances that have led to its widespread use, limits and complications of the procedure, and areas for future improvement.     

Genetics of age-related macular degeneration: current concepts, future directions

Age-related macular degeneration (AMD) is a progressive degenerative disease which leads to blindness, affecting the quality of life of millions of Americans. More than 1.75 million individuals in the United States are affected by the advanced form of AMD. The etiological pathway of AMD is not yet fully understood, but there is a clear genetic influence on disease risk. To date, the 1q32 (CFH) and 10q26 (PLEKHA1/ARMS2/HTRA1) loci are the most strongly associated with disease; however, the variation in these genomic regions alone is unable to predict disease development with high accuracy. Therefore, current genetic studies are aimed at identifying new genes associated with AMD and their modifiers, with the goal of discovering diagnostic or prognostic biomarkers. Moreover, these studies provide the foundation for further investigation into the pathophysiology of AMD by utilizing a systems-biology-based approach to elucidate underlying mechanistic pathways.     

Simple limbal epithelial transplantation: a review on current approach and future directions

Simple limbal epithelial transplantation is a recently developed technique for treating limbal stem cell deficiency caused by ocular burns. A small limbal biopsy from the donor eye, usually from the patient's healthy eye, is excised and dissected into multiple pieces. An amniotic membrane is atttached using fibrin glue on the diseased eye after removing the conjunctivalized pannus from the corneal surface. The limbal biopsy pieces are placed onto the amniotic membrane, fixed with fibrin glue, followed by bandaging of the ocular surface with a contact lens. This technique (auto simple limbal epithelial transplantation) offers easier surgical manipulations and economic advantages over other techniques for the treatment of limbal stem cell deficiency. We therefore review simple limbal epithelial transplantation along with recent modifications in the technique and case studies, including challenges and failures.     

Laser in-situ keratomileusis after penetrating keratoplasty

Laser in situ keratomileusis (LASIK) after penetrating keratoplasty has been used more commonly for the correction of myopia or myopic astigmatism and less so for hypermetropia or hyperopic astigmatism. The primary goal after LASIK in such cases is resolution of sufficient myopia and astigmatism to allow spectacle correction of the residual refractive error and decrease anisometropia. All sutures should be removed prior to LASIK and the interval between penetrating keratoplasty and LASIK should be a minimum of 1 year. Preoperative evaluation includes refraction, slit-lamp biomicroscopy, corneal topography, and specular microscopy. The technique of LASIK surgery after penetrating keratoplasty is similar to the standard procedure. However, many variations have been described. These include maneuvers during surgery such as augmentation with arcuate cuts on the stromal bed and topographically guided LASIK. Other variations are relaxing incisions followed by LASIK surgery and sequential treatment by LASIK, that is, raising of the flap as a first stage procedure followed by ablation if required, 4 to 6 weeks later after relifting the flap in the second stage. Improvement in both uncorrected visual acuity and spectacle-corrected visual acuity, as well as a decrease in spherical equivalent, cylinder, and anisometropia, has been reported in various studies. All grafts were clear and no occurrence of wound dehiscence has been reported. Intraoperative complications include hemorrhage, microkeratome failure, flap buttonhole, dislocation, and perforation. Postoperative complications include undercorrection, decentered ablation, and regression. Re-enhancements after LASIK following keratoplasty are possible with acceptable visual outcome.     

Analysis of ectasia after laser in situ keratomileusis: risk factors

PURPOSE: To examine a database of laser in situ keratomileusis (LASIK) procedures for preoperative and operative factors assumed to increase the risk for developing post-LASIK ectasia. SETTING: Private clinical practice. METHODS: A computer database was queried for eyes that had LASIK for myopic refractive errors with the following characteristics: preoperative corneal thickness 500 microm or less, mean keratometry greater than 47.0 diopters (D), patient age 25 years or younger, attempted correction greater than -8.0 D, refractive astigmatism not with-the-rule and greater than 2.0 D, and residual stromal bed thickness (RST) 250 microm or less. Flap thickness and RST were measured using ultrasound pachymetry. All recorded information was exported to MS Excel and analyzed for eyes that had ectasia. RESULTS: Of the 9700 eyes in the database, none with the above characteristics developed ectasia over mean follow-up periods exceeding 2 years. Seven eyes had multiple risk factors without ectasia. Three eyes with abnormal preoperative topography developed ectasia. CONCLUSIONS: Individual preoperative and operative factors did not in and of themselves increase the risk for ectasia. Unmeasured and unknown factors that affect the individual cornea's biomechanical stability, in combination with some suspected risk factors as well as the current inability to identify corneas at risk for developing ectatic disorders, probably account for most eyes that develop ectasia today.     

Uveal melanoma: update and future directions

In this article the author discusses advances in the treatment of ocular melanoma over the past 25 years. However, owing to metastatic disease, patient survival has not improved. Research into molecular and cellular biology and genetic factors is needed to better understand metastasis in order to improve survival.     

Partial flap during laser in-situ keratomileusis: pathogenesis and timing of retreatment

PURPOSE: To report the timing of retreatment and clinical outcomes in patients with a partial corneal flap during laser in-situ keratomileusis (LASIK), and to describe the causes of this complication. METHODS: Retrospective review of case records of four patients (4 eyes) who had a partial corneal flap during LASIK. RESULTS: The mean age of the four patients was 23 +/- 4.7 years, and mean preoperative spherical equivalent (SE) refraction was -9.1 +/- 3.1 D (range, -5.5 to -13 D). A 160 microns corneal flap was attempted during the initial treatment. Retreatment with a 180 microns corneal flap was performed at a mean of 5.1 +/- 1.6 weeks (range, 4 to 7.5 weeks) after the initial procedure. There were no intraoperative complications during retreatment. Post-LASIK mean SE refraction was -1.0 +/- 1.1 D (range, +0.38 to -2.0 D), after a mean follow up of 19 +/- 15.7 weeks (range, 7 to 42 weeks). Best spectacle-corrected visual acuity decreased in one eye from 6/5 to 6/6 and was maintained in the others. CONCLUSION: LASIK retreatment can be performed as early as one month after a partial flap, if the refraction is stable and a thicker corneal flap is created.