However, the steepening effect is twice that of the flattening effect. Given its unpredictable nature and the time frame for wound stabilisation, the procedure is usually considered only after other options such as relaxing incisions and compression sutures have been exhausted. A second curvilinear incision angled to the first is placed in the host tissue and the intervening wedge of tissue excised.
The cut edges are approximated with interrupted nylon sutures. Perry et al reported average reductions of astigmatism by as much as However considering the fairly similar results between both procedures and the prolonged visual recovery, he recommends relaxing incisions as the first procedure of choice. Laser in Situ Keratomileusis Though effective in correcting a wide range of astigmatism, all Incisional procedures are also characterised by the unpredictable nature of outcomes.
Many workers have evaluated the efficacy of laser in situ keratomileusis LASIK to correct postkeratoplasty astigmatism. In all the studies the reduction in the spherical equivalent was significantly higher than the astigmatic reductions. Enhancements are also more likely in postkeratoplasty patients, [63 ] the degree of under correction increases as the astigmatism increases.
Other workers have highlighted the topographical changes induced by making a lamellar flap with a keratome; as the flap transects the wound this in itself may reduce the amount of astigmatism and change the axis of the cylinder.
The femtosecond laser which uses lower pressures during application of the suction ring may be safer than microkeratome assisted LASIK in postkeratoplasty patients. A minimum period of at least 24 months is considered necessary before proceeding with LASIK, because of the risk of graft dehiscence. However, other factors such as degree of vascularization, whitening and scarring of the keratoplasty wound and stability of refraction and topography also need to be considered to decide the right time to perform LASIK.
The normal wound healing response may also be altered, in the setting of the removal of the epithelium and Bowmans and the width and depth of ablation in an already complex post-surgical surface. An adequate stromal bed is necessary to prevent ectasia. A prospective study by Mathew and co-workers, on PRK with the use of 0. Under corrections were more common than overcorrections especially when the spherical and astigmatic errors were more than 5D.
Toric IOLs can potentially address the twin concerns of astigmatism and cataracts. However patients with highly irregular astigmatism will not benefit from toric IOLs. In their study of 21 patients with postkeratoplasty astigmatism and cataracts, Wade and co-workers used the AcrySof toric IOLs with good predictability.
Srinivasan and co-workers have studied the benefits of customised toric IOL implantation in post keratoplasty astigmatism either as a primary intraocular implantation, or as a secondary piggyback procedure.
In their series of nine eyes they noted improvement in both visual acuity and magnitude of astigmatism. Three of their patients in this series of nine had suboptimal results after incisional surgery. Toric IOL implantation was effective in this subgroup with significant decrease in the astigmatism. Coscarelli et al documented a reduction in the corneal cylinder in patients with residual astigmatism between 3 to 5 Dioptres using the manual technique of ICRS placement.
Management of postkeratoplasty astigmatism. Curr Opin Ophthalmol. Outcomes of penetrating keratoplasty in keratoconus. Cornea ; Penetrating keratoplasty for keratoconus: a long-term review of results and complications. Journal of Cataract and Refractive Surgery. Topography-guided customized laser-assisted subepithelial keratectomy for the treatment of postkeratoplasty astigmatism.
Relaxing incision for control of postoperative astigmatism following keratoplasty. Ophthalmic Surgery. Surgical correction of high postkeratoplasty astigmatism: Relaxing incisions vs wedge resection. Archives of Ophthalmology. The surgical management of corneal astigmatism after penetrating keratoplasty.
Refractive errors following keratoplasty. Trans Am Ophthalmol Soc. Long—term survival of large diameter penetrating keratoplasties for keratoconus and pellucid marginal degeneration. Acta Ophthalmol. The effect of scleral fixation ring placement and trephine tilting on keratoplasty wound size and donor shape. Ophthalmic Surg. Effects of disparate-sized graft and recipient opening.
Trans New Orleans Acad Ophthalmol. Effects of tissue fit on corneal shape after transplantation. Inves Ophthalmol Vis Sci. Herbert E Kaufman. Companion Handbook to The Cornea.
Second Edition. Postkeratoplasty astigmatism control: single continuous suture adjustment versus selective interrupted suture removal. Corneal topography for selective suture removal after penetrating keratoplasty. American Journal of Ophthalmology. Quantitative descriptors of corneal topography. A clinical study. Binder PS. The effect of suture removal on postkeratoplasty astigmatism. Clinical and surgical factors influencing corneal graft survival, visual acuity, and astigmatism: Corneal Transplant Follow-up Study Collaborators.
Different suturing techniques variously affect the regularity of postkeratoplasty astigmatism. Rapid suture management of post-keratoplasty astigmatism. Controlled reduction of postkeratoplasty astigmatism. Long-term results of penetrating keratoplasty using a single or double running suture technique.
Graefes Arch Clin Exp Ophthalmol. An adjustable single running suture technique to reduce postkeratoplasty astigmatism; a preliminary report. Comparison of the effect of three suturing techniques on postkeratoplasty astigmatism in keratoconus. Sequential selective same-day suture removal in the management of post-keratoplasty astigmatism. Price Jr. Progression of visual acuity after penetrating keratoplasty. Caroline P and Zilge L. Postsurgical correction with contact lens fitting following penetrating keratoplasty.
Clinical Contact Lens Practice. Bennett and B. Weissman, Eds. Three axis ellipsoidal fitting of videokeratoscopic height data after penetrating keratoplasty. Current Eye Research. Scleral contact lenses for visual rehabilitation after penetrating keratoplasty: long term outcomes.
Cont Lens Anterior Eye. From Wikipedia, the free encyclopedia. Redirected from DJI company. This article is about the Chinese company. For other uses, see DJI disambiguation. Trade name. Technology Consumer electronics Videography Photography.
Shenzhen , Guangdong. Main article: Phantom UAV. Main article: Mavic UAV. Main article: Osmo camera. Jan 27, Retrieved Jan 30, Retrieved Uplift Drones. June 20, January 3, The Economist.
Retrieved 19 April The Wall Street Journal. Retrieved March 2, Retrieved 22 December DJI Technology. The New York Times. What Are The Best Drones? Drones Den. June 15, Retrieved June 19, DJI Enterprises. Oct 15, Retrieved Nov 1, Retrieved 8 May Archived from the original on My Drone Lab. Retrieved 20 March Retrieved 12 September News Ledge. DJI Official. Drone Addicts. Clinical Features And Stages Of NVG The disease passes through four stages — Pre-rubeosis stage, Pre-glaucoma stage, Open angle glaucoma stage and Angle closure glaucoma stage, each one having differing clinical features.
Laser photometry or fluorescein iris angiography is helpful in detecting early leakage of iris vessels. Pre-glaucoma stage: Rubeosis iridis stage — At this stage, variable amounts of neovascularization Figure 3 can be found at pupillary margin, iris surface and in the angle.
Neovascularization must be looked for carefully under high magnification Figure 4 on the iris and in the angle by gonioscopy at every visit. The iris should be examined before dilatation of the pupil and pupillary margins and margins of iridotomy should be carefully looked at for new vessels, which appear like knuckles of fine vessels. Although neovascularization is usually seen first at peripupillary area, a thorough gonioscopy should be performed since NVA can sometimes precede rubeosis iris.
Characteristic features of this stage are normal IOP, unless pre-existing concomitant primary glaucoma is present. Patients are usually asymptomatic at this stage. Open angle glaucoma stage- At this stage, IOP begins to rise and stays elevated. In some cases, the IOP may rise suddenly resulting in acute-onset glaucoma. Rubeosis iridis in this stage is more florid and is often associated with anterior chamber inflammatory reaction.
Due to fragile nature of the new vessels, hyphema can also present sometimes at this stage. Gonioscopy shows an open angle but with more intense neovascularization. Angle closure glaucoma stage- Most patients present or are detected at this stage. The contraction of fibro vascular membrane in the angle leads to progressive synechial angle closure, ectropion uveae and flat, smooth, glistening appearance of the iris. Gonioscopy reveals varying degrees of peripheral anterior synechiae or complete angle closure may be present at this stage.
The IOP is usually very high and can even go up to 60 mmHg. Rubeosis is usually severe with possible hyphema and moderate anterior chamber inflammation at this stage. Conjunctival congestion and corneal edema are frequently present. Glaucomatous optic nerve damage is often moderate to advance. Visual acuity may also be severely affected. If not treated appropriately it can lead to glaucomatous optic atrophy.
Management of NVG General principles for treatment of NVG are aimed at identifying the underlying etiology and its timely and adequate treatment to prevent the development and progression of NVG. Prophylactic Treatment The management strategy involves registering the predisposing factors and having a high index of suspicion in the above mentioned conditions. It is necessary to closely follow these eyes and manage patients adequately to reduce the incidence of neovascularization and to minimize visual loss.
Ultra-wide-field fundus fluorescein angiography [11 ] offers the possibility of evaluating and quantifying peripheral retinal perfusion and vascular pathology in fundus disease. Such patients deserve careful monitoring of iris and angle, even after standard course of PRP, so that further retinal ablation can be done if new vessels develop or progress in the anterior segment.
In OIS, ocular neovascularization is not always associated with retinal capillary non-perfusion on FFA, even in eyes with diabetes mellitus. Its role in management of NVG is unclear, and it has not proven to be beneficial in preventing synechial closure of angle or advanced NVG. Hyperosmotic agents may also be required. Topical prostaglandin analogues can be tried though they may increase ocular inflammation.
Miotics are contraindicated as they can increase inflammation and discomfort. Anti- inflammatory drugs — Frequent administration of topical steroids and cycloplegics are recommended to reduce inflammation that is inevitably present. Anti- Angiogenic drugs — Several studies propose the use of anti-VEGF agents with traditional treatments such as PRP [19 ] with or without additional surgery and vary in the timing, combination, and place of injection intracameral or intravitreal, or both simultaneously.
The most frequent recommendation by various authors for treatment of neovascularization is the adjunct combination of intravitreal bevacizumab and PRP or bevacizumab alone when visibility of the posterior segment is difficult due to opacities of the media e. Most studies mention similar dose for intravitreal and intracameral use 1. It is also effective in reducing intraocular inflammation and pain and in few reports IOP lowering has been noted in the open angle stage.
In advanced cases of NVG it can be used as a therapeutic window for PRP and also surgical intervention for IOP control can be performed with much less risk of failure, hemorrhage and inflammation. In cases where PRP is not possible due to poor retinal view, intravitreal Bevacizumab can be given followed by Trabeculectomy with Mitomycin C.
Anterior retinal cryopexy ARC may be useful in cases of compromised posterior segment view and where availability or affordability of anti VEGF is an issue. Medical management with intravitreal anti-VEGF along with retinal ablation wherever possible may be sufficient to control the IOP in the open angle stage of NVG, but in advanced stage with synechial angle closure surgical intervention for IOP lowering is often required.
Surgical Management of NVG The three surgical modalities often employed are trabeculectomy, tube shunts and cycloablation. The choice of surgical procedure is made depending upon underlying disorder as well as the clinical characteristics of each patient i.
Trabeculectomy Intraoperative use of anti-fibrotic agents like Mitomycin C i. MMC is recommended to reduce the risk of bleb failure due to subconjunctival scarring. High dose 0. Surgical intervention should be planned within a week of injection of anti-VEGF. Combined cataract and glaucoma surgery can be planned if media is hazy due to cataract, followed by PRP whenever possible. In cases of hazy retinal view due to a cause like vitreous hemorrhage, if after a short interval of observation the media clarity does not improve, pars plana vitrectomy PPV with endolaser EL photocoagulation may be considered.
Repeat intravitreal injections of bevacizumab may be required. Many surgeons may opt for glaucoma drainage implant placement at the time of PPV and EL, after medical management with drugs and anti-VEGF agents, particularly if synechial angle closure is evident or suspected. These studies have looked at intracameral, intravitreal, and subconjunctival administration. The use of releasable sutures and laser suturolysis post-operatively can help titrate IOP in early post-operative period.
A closer follow up is required for these patients. Sub conjunctival use of 5-Fluorouracil 5-FU or MMC can be considered post-operatively in cases which show early signs of risk of failure or aggressive vascularization.Willkommen auf dem offiziellen Youtube Channe von Ormed GmbH – a DJO Global Company. DJO Global ist ein weltweit führender Anbieter für die Versorgung mit or.