Presenting authorDr K V Satyamurthy, Dr Jaysheel V NazareM.M.Joshi eye institte

Hubli,India

TransPRK (Transepithelial Photorefractive Keratectomy) For the Treatment of Low to Moderate Myopia with Astigmatism

“NO TOUCH” PROCEDURE

Authors have no financial or proprietary interest in any material or methods

Introduction

Transepithelial PRK

• Most commonly indicated in eyes which cannot undergo

LASIK procedure due to inadequate corneal thickness

(estimated residual stromal thickness beneath the flap after the ablation would have

been less than 250 µm)• No corneal flap created• Both epithelium and stroma are ablated in single procedure,

decreasing overall treatment time and minimizing risk of

corneal dehydration.

PURPOSE OF STUDY

• To evaluate efficacy of transepithelial Photorefractive

keratectomy (transPRK) for the treatment of low to

moderate myopia with astigmatism, using the Amaris

500 Hz laser platform.

METHODSInclusion Criteria• Phakic patients with low to moderate myopia (-1.0 to -6.0 D of myopia with -1.0D to -4.0D

astigmatism) Spherical

equivalent from -3.5 to -8D.• Healthy myopic patients 18 years or older.• Vision correctable to at least 20/20 bilaterally.• written informed consent form signed by patient.• Refractive status to be stable for at least 1 year.

• Corneal pachymetry greater than 480µm. The estimated

residual Stromal thickness after ablation would have

been 300-350 µm

• Prior to preoperative evaluation, hard (PMMA) contact

lens discontinued for at least 3 weeks and soft lens

discontinued for at least 3 days.

• Pupil diameter of equal or less than 7mm under scotopic

conditions.

Complete Ophthalmologic Examination - Uncorrected (UDVA) and corrected (CDVA) distance visual

acuities

- Manifest and cycloplegic refractions

- slitlamp evaluation of the anterior segment and the fundus

- Applanation tonometry and tear-film assessment

Preoperative refractive workup included - Combined Placido-Scheimpflug Imaging Based Topography

System (SIRIUS)

- Ultrasonic Pachymetry

Total of 29 subjects, were enrolled instudy.

Preoperatively,

- 0.25/0.5 mg of oral alprazolam.

- Topical drops of Proparacaine (0.5%) instilled in the eye to be treated

During procedure, epithelium and stroma were ablated in a

single step using transepithelial PRK nomogram of Amaris laser's

ORK-CAM software.

- After ablation 0.02% Mitomycin-C solution applied 30

seconds.

- Cold BSS irrigation.

- High-O2 Content (59%) soft contact lens placed. - Ofloxacin (0.3%) and fluorometholone (0.1%) drops.

Post-operative Care and Follow-up

- Preservative-free artificial tears.

- Epithelial healing assessment on day 1and 3.

- CL removed once epithelium healed completely

- Fluorometholone drops tapered over 2-3 months.

At each follow-up visit (at1 week, at 1 month, and at 3 months) the UDVA, CDVA, and Corneal evaluation was done.

Haze grading using the Fantes et.al system

0 = no haze;

+0.5 = trace haze on oblique illumination;

+1.0 = corneal cloudiness not interfering with the

visibility of fine iris details;

+2.0 = mild effacement of fine iris details;

+3, +4 = details of the lens and iris not discernible.

RESULTS

Parameters Values

No of Patients 29

Age(yrs)Mean

24

Gender - Male - Female

1316

Number of eyes - Right - Left

1514

RESULTS

Parameters Preop Post op 1month

(p value)Post op 3month(p value)

Mean UDVA (logMAR)

1.08 0.11(0.000) 0.11(0.000)

- Mean Spherical Equivalent

-3.732758621

RESULTSParameters Preop Postop

1monthPostop 3month

Mean CCT (microns)

506 421(o.ooo) 424.9(0.000)

Mean SimK1 (D) 43.95 40.34(0.000) 40.43(0.000)

Mean SimK2 (D) 45.11 41.08(0.000) 41.16(0.0000

Mean Pupil (mm) 3.45 3.50(0.000) 3.67(0.007)

RESULTSParameters Preo

pPostop 1month(p value)

Postop 3month(p value)

Mean Thinnest pachy

503.5 418.7(0.000)

425(0.000)

Mean Thickness At Apex

529.8 590.7(0.000)

602.7(0.000)

Mean Cornea Volume

55.89 54.65(0.000)

54.76(0.000)

Mean LSA 1.02 2.26(0.000)

1.12(0.000)

Mean MPP 44.18 39.73(0.000)

39.52(0.000)

Parameters Preop Postop 1month(p value)

Postop 3month(p value)

Mean SIF 0.10 0.15(0.000)

0.24(0.000)

Mean SIB -0.03 -0.02(0.000)

-0.03(0.000)

Mean KVF 3.75 8.96(0.000)

9.17(0.000)

Mean KVB 12.79 16.75(0.000)

17.34(0.000)

RESULTS

Parameters

Preop Postop 1month(p value)

Postop 3month(p value)

Mean BCVF

0.16 0.13(0.000) 0.24(0.000)

Mean BCVB

0.06 0.09 (0.000) 0.09(0.000)

Mean BCVT

0.1 0.11(0.000) 0.10(0.000)

Parameters

Mean Optical Zone(mm)

6.41

Mean Treatment Time (ablation)

42.58 s

RESULTS

POST-OPERATIVE CORNEAL HAZE GRADES Total

o 0.5 1 2 3-4

1 Month 0 24(82.75%)

5(17.24%) 0 0 29

3 Month 22(75.86 %)

7(24.13%)

0 0 0 29

CONCLUSION

• Safety, predictability and efficacy of the Schwind Amaris advanced surface ablation nomogram(TransPRK) for the treatment of mild to moderate myopia with astigmatism in eyes with thinner corneas not suitable for LASIK procedure was found to be better than the existing alcohol assisted PRK technique.