POSTERIOR SEGMENT EVALUATIONS OF REFRACTIVE SURGERY Ghanbari MD 1389:10:30

VITREORETINAL COMPLICATIONS  Macular complications.  Retinal complications.  Optic nerve complications.

 Macular hemorrhage  Subhyaloid hemorrhage  Full-thickness macular hole  CNV  CME  CSR

 Optic neuropathy (several reports)  Changes in NFL

 It is important to adopt preventive measurs for optic neuropathy after LASIK

 Retinal detachment.  Vein occlusion

 Vitreoretinal stress is induced at the posterior vitreous base during a PVD after LASIK.

 It is very important to inform patients LASIK only corrects the refractive aspect of myopia, and vitreoretinal complications after LASIK although infrequent may occur.

 Mechanisms of complications of posterior segment:

 SHOCK WAVES It was found that the excimer laser provokes a shock wave velocity of 3.3 km/sec at 40 nanoseconds and that it generates a pressure of up to 100 atmospheres.

Possible Theoretical Pathogenetic Mechanisms for the Effect of Corneal Laser Surgery on the Retina

 Sudden increase and decrease in the IOP during suction or release of the keratome suction ring might exert a mechanical stretch on the vitreous base that may cause retinal detachment.  The high IOP may cause retinal circulation disturbance, which may lead to the development of foveal hemorrhage due to possible high reperfusion pressure.

 Miotics  Moreover, nowadays miotics are not standard practice in refractive surgical procedures, and are in fact discouraged, as they may shift the location of the natural entrance pupil, leading to a decentered procedure.

Round retinal hole in area of lattice retinopathy. The risk of progression to a retinal detachment is small, unless the hole is in the fellow eye to one that has had a retinal detachment

Angioid streaks

Macular haemorrhage (white arrow) associated with choroidal neovascularisation in high myopia

 Central serous chorioretinopathy following LASIK for hyperopia.

 Retinal phlebitis after LASIK

 Uveal effusion following laser in situ keratomileusis (LASIK) for hypermetropia

Appearance of fundus at 1 month after laser-assisted in situ keratomileusis showing the grey ring around the optic disc.

 Some of these complications can be prevented.

 It is recommended that patients scheduled for refractive surgery be examined carefully with indirect ophthalmoscopy and scleral depression under pupillary dilation in order to detect any myopic peripheral lesion that requires immediate treatment before refractive surgery can be performed.

 Recommend that patients undergoing refractive surgery have a detailed fundus examination to detect predisposing vitreoretinal pathology.

 Because the incidence of retinal detachment in eyes with asymptomatic lattice degeneration is relatively low, prophylactic treatment of the retina in eyes with asymptomatic lattice degeneration before excimer laser surgery is not necessarily recommended.

 Recommend that subclinical retinal detachments (retinal detachment localized around the break, not extending posterior to the equator) be managed according to the recommendations of the American Academy of Ophthalmology.

 Symptomatic subclinical retinal detachments should be treated.  Asymptomatic subclinical retinal detachments in high myopes probably should be treated.

 As is generally well accepted, symptomatic retinal lesions should be prophylactically treated regardless of future laser surgery.

White with pressure

 Cryopexy,  Laser retinopexy,  Pneumatic retinopexy,  Vitrectomy without scleral buckling  tend not to change the shape or length of the globe and should be preferred to repair RRD.

 Prophylactic treatment of vitreoretinal pathology before LASIK does not guarantee the prevention of post-LASIK vitreoretinal complications.

 Overall, serious retinal complications following refractive surgery do not appear to happen at significantly higher rates than in the general myopic population, which is inherently predisposed to retinal pathology.

 Macular disease  High myopia and lacquer cracks.  Angioid streaks and traumatic choroidal ruptures  Stage 1 macular holes.  Eyes that are at risk of needing vitreoretinal surgery in the future have a relative contraindication to LASIK.