prk ..... is it a good alternative to lasik ????
TRANSCRIPT
PRK ….Is it a good alternative to LASIK ?
Dr. Amr Mounir.MDLecturer of OphthalmologySohag University Hospital
By
To answer the title question we should ask ourselves another group of questions
First: Why doctors return to PRK again ?
PRK
LASIK
Second: Is LASIK a hazardous technique ?
Third: What are benefits of PRK over LASIK ?
LASIK
PRK
First: Why doctors return to PRK again ?
Easy technique
No flap related complications
Less ectasia
Less cost
Second: Is LASIK a hazardous technique ?
Hazardous in the following conditions
1. Long-term safety
2. Flap related complications
3. Suction high pressure effect on posterior
segment
Third: What are the benefits of PRK over LASIK?
More safe → No flap → No damaging effect in
corneal architecture → Maintained corneal
stability → Less ectasia
Less thinning → More residual bed
Can be done for suspicious corneas
No effect on posterior segment
No dry eye
Economic AspectNo Blade
However, after answering the previous questions
The last question is:• Why great evolution had occurred from PRK
to LASIK in the beginning of excimer laser corneal refractive surgeries
PRK is not a completely safe technique, it has its own problems.
Problems of PRK1. Haze:• Early: Due to early removal of therapeutic
contact lens (bad healing)• Late: Subepithelial fibroblasts proliferation:• UVA exposure• High correction
PRK haze
Problems of PRK
2. Epithelial healing problems:• Persistent defect • Infection
3. Regression in refraction4. Slow rehabilitation5. Scar formation
POST.PRK infection
Post.PRK Scar
Benefits of LASIK
1. Time honored procedure2. Stable refraction3. Rapid rehabilitation 4. No haze5. No epithelial healing problems
How can we increase LASIK safety ?
By creating ultrathin flaps by:1. Sub bowman’s keratomileusis (SBK)2. Femtocreated flaps
Indications of PRK
• Thin cornea • Suspicious cornea• In combination with corneal collagen CXL
in keratoconic eyes (Athens protocol)
Advanced Surface Ablation
Cataract & Refractive Surgery Today EUROPE May 2013
Advanced Surface Ablation
1. LASEK, in which the epithelium is removed with alcohol
2. Epi-LASIK, in which the epithelium is mechanically lifted without adjunctive agents.
In both procedures, laser photoablation is performed just above the Bowman layer
Advantages 1. Done in high myopes (–6.00 to –10.00 D).2. Avoids all the flap-related complications
seen in LASIK, including incomplete flaps, free caps, buttonhole flaps, flap striae, dislocated flaps, flap melts, epithelial ingrowth, and DLK.
3. Safety in posterior segment.
Improvement of PRK quality of vision
How to avoid haze in advanced ablation ?
1. Preoperative : Ask thoroughly about healing of wounds in body as general ( over healing e.g: skin Keloids).
How to avoid haze in advanced ablation ?
2. Intraoperative : - Mitomycin C application (0.02%). - Washing the bed with cold BSS every 3 Ds to lessen the thermal effect of laser ablation
How to avoid haze in advanced ablation ?
3. Postoperative : - Avoid early removal of contact lens before complete epithelial healing.(early onset haze)- Long term topical steroids therapy .(late onset haze)- Avoid sunrays exposure.( Late onset haze)
PRK is a good alternative to LASIK as regard safety and corneal stability, however it carries some problems especially haze and epithelial healing problems.
LASIK is better in straight forward cases especially with ultrathin flaps.
Thank you