POSTERIOR SEGMENT EVALUATIONS OF REFRACTIVE SURGERY

Ghanbari MD1389:10:30

VITREORETINAL COMPLICATIONS

Macular complications. Retinal complications. Optic nerve complications.

MACULAR COMPLICATIONS

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

OPTIC NERVE COMPLICATIONS

Optic neuropathy (several reports) Changes in NFL

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

RETINAL COMPLICATIONS

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:

POSSIBLE THEORETICAL PATHOGENETICMECHANISMS FOR THE EFFECT OF CORNEALLASER SURGERY ON THE RETINA SHOCK WAVESIt 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 PathogeneticMechanisms for the Effect of Corneal

Laser Surgery on the Retina

IOP RISE AND DECOMPRESSION

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.

POSSIBLE THEORETICAL PATHOGENETICMECHANISMS FOR THE EFFECT OF CORNEALLASER SURGERY ON THE RETINA 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 inarea of lattice retinopathy.The risk of progression to a retinaldetachment is small, unless the hole is in thefellow eye to one that has had a retinaldetachment

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.

PREVENTION

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.

CONCLUSION

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.

RELATIVE CONTRAINDICATIONS TO LASIK

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.