Year : 2017 | Volume
: 55 | Issue : 3 | Page : 250--252
Shruti Nishanth, Murali Ariga
Department of Paediatric Ophthalmology, M.N. Eye Hospital Private Limited, Chennai, Tamil Nadu, India
Dr. Shruti Nishanth
M.N. Eye Hospital Private Limited, Chennai, Tamil Nadu
|How to cite this article:|
Nishanth S, Ariga M. Journal scan.TNOA J Ophthalmic Sci Res 2017;55:250-252
|How to cite this URL:|
Nishanth S, Ariga M. Journal scan. TNOA J Ophthalmic Sci Res [serial online] 2017 [cited 2019 Nov 22 ];55:250-252
Available from: http://www.tnoajosr.com/text.asp?2017/55/3/250/226865
1. Multifocal Intraocular Lenses: an Overview
Alio JL, Plaza-Puche AB, Férnandez-Buenaga R, Pikkel J, Maldonado M. Multifocal intraocular lenses: An overview. Surv Ophthalmol 2017;62:611-34.
Introduction: This article is a review of 178 peer-reviewed published studies on multifocal lenses (MfIOL) up until January 2016. Design of Multifocal Lenses: MfIOLs are of three types: refractive, diffractive, or a combination of both. Refractive lenses are dependent on pupil size and centration. Diffractive lenses are less pupil size dependent and are more tolerant to the kappa angle and decentration. Patient Selection: One should avoid implanting MfIOL in patients with unrealistic expectations and those with an overly critical personality. The complete contraindications for an MfIOL are implantation in children and in established glaucoma. The relative contraindications are ocular surface disease, professional night drivers, and maculopathy. Although bilateral MfIOL is the most favorable, unilateral implantation may also be as effective, especially in young patients. Neuroadaptation: MfIOLs, due to their design, induce a further change to the already existing ocular aberrations, thus creating a more complex challenge for the brain to adapt to the new image on the retina. Hence, a minimum period of 3 months can be given for neuroadaptation. Younger patients can adapt faster. Visual Outcomes: Diffractive lenses provide much better distance, near, and intermediate visual outcomes (in that order), as compared to refractive lenses. Spectacle independence was 80% or more for distance, 100% for intermediate vision, and 70% for near vision. Complications/Side-effects: The most common postoperative complaints were blurry vision and photic sensation (3.5 times than monofocal). Blurry vision was positively correlated with residual ametropia, dry eye, and posterior capsule opacification (PCO). Photic sensation was correlated with dry eye, intraocular lens (IOL) decentration, and PCO. Around 80% of complaints can be resolved with conservative treatment, 13% may require some intervention, while 7% require an IOL exchange. Management/Prevention of Complications: Decentration: Argon laser iridoplasty may be planned. The argon laser settings for the iridoplasty are 0.5 s, 500 mW, and 500 μm. Intraocular Lens Tilt: The use of hydrophobic lens and capsular tension rings improve stability of IOL and prevent capsular phimosis. Small Pupil: Topical cyclopentolate or 360° Argon iridoplasty (0.5 s, 500 mW, and 500 μm) can be planned. Large Pupils: Brimonidine tartrate 0.2% to decrease mydriasis at night is a classical solution. Residual Refractive Error: Laser-assisted in situ keratomileusis has the highest efficacy; other options being photorefractive keratectomy, IOL exchange and piggyback lenses. IOL exchange should be reserved for extreme cases such as unacceptable dislocation or large residual refractive error. Dry Eye: Preservative-free artificial tears, cyclosporine, punctual plugs, and platelet-rich plasma drops.
Take home message
Multifocal lenses may be provide a good visual outcome in most patients, provided careful patient selection is exercised, with proper prior education and postoperative time for neuroadaptation.
2. A review of Adaptive Optics Optical Coherence Tomography: Technical Advances, Scientific Applications, and the Future
Jonnal RS, Kocaoglu OP, Zawadzki RJ, Liu Z, Miller DT, Werner JS, et al. A review of adaptive optics optical coherence tomography: Technical advances, scientific applications, and the future. Invest Ophthalmol Vis Sci 2016;57:OCT51-68.
This article is a review about literature published on adaptive optics (AO), which is the latest in the league of all optical coherence tomography (OCT) advancements such as ultra-high resolution OCT, enhanced-depth OCT, and OCT angiography. It has been used to improve the transverse resolution of ophthalmoscopes to foster in vivo study of the retina at the microscopic level. Currently, it is a tool used by basic researchers, but multiple studies have endeavored to incorporate it into clinical practice. AO works on the principle of “Diffraction-limited imaging,” which is achieved by measuring and correcting ocular monochromatic aberrations over a dilated pupil. This is implemented with a Shack-Hartmann wavefront sensor and deformable mirror. The deformable mirror molds itself to the aberrations of the eye to the tune of 110 corrections/second thereby negating it. This allows for greater resolution volume of the retinal layers by 36 times. One of the major limitations of AO-OCT systems is the presence of eye motion artifacts, due to the higher magnification offered. This is eliminated by increasing the speed of the AO to 1 million A-scans/second. The AO-OCT can image the cone outer tip segments (COST), the anatomic origin of the retinal bands and the photoreceptor function by rate of renewal of outer disc segments. It can be applied in age-related macular degeneration (loss in inner segment/outer segment [IS/OS] reflectivity), glaucoma (lamina cribrosa imaging, photoreceptor density, and retinal nerve fiber layer bundles), diabetic retinopathy (microvasculature study), and efficacy of Stem cell therapy.
Take home message
AO-OCT is an exciting new prospect in technology that can help in greater detailing of anatomic as well as functional changes in the retinal layers such as COST, photoreceptor renewal, IS-OS details, and microvasculature, and may well be the future of imaging.
3. Bimatoprost Sustained-Release Implants for Glaucoma Therapy: 6-Month Results from a Phase I/ii Clinical Trial
Lewis RA, Christie WC, Day DG, Craven ER, Walters T, Bejanian M, et al. Bimatoprost sustained-release implants for glaucoma therapy: 6-month results from a phase I/II clinical trial. Am J Ophthalmol 2017;175:137-47.
This study is an interim 6-month report of an ongoing 24-month Phase 2 clinical study comparing intracameral Bimatoprost Slow Release implant versus topical bimatoprost 0.03%. The implant consists of micronized bimatoprost incorporated into biodegradable polymer matrix. It can be injected intracamerally through a preloaded applicator system, into the anterior chamber, where it will settle in the inferior angle. After a washout period, 75 eyes with established glaucoma were implanted with 6,10,15 or 20 μg of bimatoprost sustained-release (SR) in one eye, with fellow eye started on topical bimatoprost once a day dosing. Overall, the mean IOP reduction ranged from 7.2 to 9.5 mm Hg after a single administration of bimatoprost SR (at 16 weeks follow-up) and was similar to the reduction of 8.4 mm Hg seen in eyes with topical bimatoprost. The most common adverse events in study eyes were conjunctival hyperemia, foreign body sensation, eye pain, increased lacrimation, conjunctival hemorrhage, and punctate keratitis. Patient satisfaction was noted to be extremely good, with 83.3% opting for a reinjection at 6 months.
Take home message
Intracameral bimatoprost SR implant provides good and prolonged (6 months) IOP control, as compared to topical bimatoprost, without the hassles of adherence and also avoids the periocular side-effects of topical bimatoprost such as eyelash growth and discoloration.
4. Optical Coherence Tomography Angiography Vessel Density in Healthy, Glaucoma Suspect, and Glaucoma Eyes
Yarmohammadi A, Zangwill LM, Diniz-Filho A, Suh MH, Manalastas PI, Fatehee N, et al. Optical coherence tomography angiography vessel density in healthy, glaucoma suspect, and glaucoma eyes. Invest Ophthalmol Vis Sci 2016;57:OCT451-9.
This study compared the retinal nerve fiber layer (RNFL) thickness using spectral domain optical coherence tomography (SD-OCT) with the vessel density using OCTA in healthy, glaucoma suspect, and glaucoma patients. A total of 261 eyes of 164 participants with good quality OCTA images from Diagnostic Innovations in Glaucoma Study were selected for the study. Two vessel density measurements extracted from the RNFL were analyzed: (1) circumpapillary vessel density (cpVD) measured in a 750-micron-wide elliptical annulus around the disc and (2) whole image vessel density (wiVD) measured over the entire image. The wiVD and cpVD values were significantly lower in glaucoma eyes, followed by glaucoma suspect eyes, and healthy eyes. The area under the receiver operating characteristic (AUROC) curves is another parameter used to measure the diagnostic accuracy for healthy and glaucoma eyes. Higher the number, more accurate is the correlation. The AUROC for discriminating between healthy and glaucomatous eyes was highest for wiVD, followed by RNFL thickness and cpVD.
Take home message
Decreased vessel density over entire image of retina (wiVD), measured using OCT-A, correlates well with RNFL loss measured using SD-OCT and can be used as a predictor for glaucoma diagnosis and progression.
5. Evaluating Polypoidal Choroidal Vasculopathy With Optical Coherence Tomography Angiography
Wang M, Zhou Y, Gao SS, Liu W, Huang Y, Huang D, et al. Evaluating polypoidal choroidal vasculopathy with optical coherence tomography angiography. Invest Ophthalmol Vis Sci 2016;57:OCT526-32.
This was a retrospective observational case series of 13 eyes, which compared the imaging of polypoidal choroidal vasculopathy (PCV) in optical coherence tomography angiography (OCTA) and indocyanine green angiography (ICGA)-angiography. ICGA is an invasive method, with minimal but reported complications, while OCTA is a noninvasive method using a 70 kHz spectral domain optical coherence tomography and SSADA algorithm to distinguish blood flow from static tissue. Two parameters were studied: Branching vascular networks (BVN) and polypoidal lesions. BVN was detected better by the OCTA than ICGA. The patterns of the BVN on OCTA showed as seafan, medusa, and tangle. The BVN was located anatomically in the space between the RPE and Bruch's membrane on OCTA. The polypoidal lesions showed better on ICGA than OCTA, and could not be detected with OCTA in mild cases. The patterns of the polyps on OCTA showed as nodular, ring, dot, and cluster. The polyps were located anatomically under the top of the pigment epithelial detachment on OCTA.
Take home message
OCTA is a safe, effective, and noninvasive method to identify the branching vascular networks (BVN) and polypoidal lesions of PCV, and also describe the pattern and locate the lesion anatomically. However, ICGA is a better tool to map the polypoidal lesions and OCTA is a better tool to map the BVN.
6. Positive Vitreous Pressure: Pathophysiology, Complications, Prevention, and Management
Chronopoulos A, Thumann G, Schutz J. Positive vitreous pressure: Pathophysiology, complications, prevention, and management. Surv Ophthalmol 2017;62:127-33.
Chronopoulos A, Thumann G, Schutz J. Positive vitreous pressure: Pathophysiology, complications, prevention, and management. Surv Ophthalmol. 2017 Mar-Apr; 62(2):127-133.
This was a major review article detailing all aspects of PVP. PVP is a phenomenon characterized by forward displacement of the lens-iris diaphragm, following a drop in intraocular pressure, during anterior segment intraocular surgery that can lead to a cascade of intraoperative complications. The article goes on to elucidate the signs of PVP such as shallowing of anterior chamber, iris, vitreous or lens prolapse, and zonular or posterior capsular rupture. The pathophysiology of PVP can be explained based on 2 mechanisms: (1) External compression of the globe causing vitreous cavity volume reduction (e.g.,) ocular muscle tension, external instrument pressure, and orbital tissue pressure and (2) Acute intraocular intumescence causing vitreous cavity volume reduction (e.g.,) PK, suprachoroidal effusion caused by high myopia, chronic glaucoma, anticoagulation, aqueous misdirection, and uncontrolled systemic hypertension. Closed chamber phaco, preoperative mannitol, use of viscoelastics, preoperative good akinesia, massage with adequate anesthetic drug and use of Flieringa ring in Penetrating keratoplasty are all ways to reduce risk PVP. Once PVP does occur, it will be prudent to immediately close the surgery with sutures and air bubble. Pars plana vitrectomy can be tried later in planned setting.
Take home message
Positive vitreous pressure is a preventable by closed chamber techniques and good patient prep before surgery. Once it occurs, the best treatment remains - to close the surgery and reassess.
7. Relationship between Central Retinal Vessel Trunk Location and Visual Field Loss in Glaucoma
Wang M, Wang H, Pasquale LR, Baniasadi N, Shen LQ, Bex PJ, et al. Relationship between central retinal vessel trunk location and visual field loss in glaucoma. Am J Ophthalmol 2017;176:53-60.
This was a retrospective cross-sectional study of 421 eyes that studied the horizontal central retinal vessel trunk location (CRVTL) on glaucomatous optic discs and sector-specific visual field (VF) loss. CRVTL was defined as the ratio between the distance from CRVT to temporal disc border and the horizontal disc diameter. First, the optimally fitted ellipse around the Optic nerve head border was calculated by optical coherence tomography. Following that, a trained observer marked the CRVTL on the temporal-nasal direction of the ellipse on each fundus image, and the ratio was calculated. The Garway-Heath scheme and Annular scheme was used to determine the sectoral VF loss, corresponding to the CRVTL. It was found that CRVT nasalization was positively correlated to central VF loss. It was strongly correlating for moderate and severe glaucoma than mild glaucoma. CRVTL nasalization is not necessarily the result of glaucoma progression but probably a stable anatomic parameter that acts as a risk factor to develop central VF loss in the course of glaucoma. This can be explained by: (1) Nasalized CRVTL may result in less mechanical support for lamina cribrosa in the temporal region, making it more susceptible to glaucomatous damage, (2) Nasalized CRVTL may affect the vascular supply in the temporal region, leading to thinning of retinal nerve fiber layer in the macular region.
Take home message
A nasal location of the central retinal vessel trunk is significantly correlated to central VF loss, especially in moderate and severe glaucoma. CRVTL nasalization may therefore be a structural biomarker of central VF loss in glaucoma.
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Conflicts of interest
There are no conflicts of interest.