change in the phoria state of the eye after refractive surgery for myopia
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Change in the Phoria state of the eye after refractive surgery for myopia. Dr Umang Mathur , Dr Archana Gupta, Dr Suma Ganesh Dr Shroff’s Charity Eye Hospital, Daryaganj , New Delhi - PowerPoint PPT PresentationTRANSCRIPT
Change in the Phoria state of Change in the Phoria state of the eye after refractive surgery the eye after refractive surgery
for myopiafor myopiaDr Umang Mathur, Dr Archana Gupta, Dr Suma GaneshDr Umang Mathur, Dr Archana Gupta, Dr Suma GaneshDr Shroff’s Charity Eye Hospital, Daryaganj, New Dr Shroff’s Charity Eye Hospital, Daryaganj, New
Delhi Delhi
The authors do not have any proprietary or financial interest in a product, method or material used in this study. There are no
competing interests in this study
Aim
To study the change in the phoria state of the eye after refractive surgery for myopia
Design: Prospective non comparative study
All patients interested in refractive surgery were screened
MethodsInclusion criteria
– Bilateral myopia– Age>18 yrs– Willingness for refractive
surgery– Eligibility for refractive
surgery– Anisometropia < 1D
Exclusion criteria– Unilateral – Amblyopia – Presence of any other
ocular disease– Any previous intraocular
surgery– Patient not willing for
refractive surgery– Patients unsuitable for
refractive surgery– Planned monovision
MethodsPre operative work upRoutine LASIK work up
including– The spectacles worn were
evaluated for the power, presence of a bifocal segment and any prism if incorporated
For correction, the manifest refraction was aimed for in all cases - no deliberate over or under-corrections attempted.
Orthoptic evaluation– Head posture evaluation– Hirschberg test– Cover test– Prism bar cover test for
distance and near (and in all positions of gaze) both with and without glasses wherever possible
– Extra ocular movements– Near point of convergence, near
point of accommodation– Fusional amplitudes– Worth 4 dot test for
fusion/suppression– Ran dot E for stereopsis.
Patients with a deviation of greater than or equal to three prism diopters* were included in the study
Methods
Standard LASIK technique
LASIK flap created with a Hansatome at 160 or 180 microns depth and the stromal bed was ablated using a Visx star S4 excimer laser
Postoperative evaluations – one week– six weeks– three months – six months post
Orthoptic evaluation at each visit
Any symptoms/ complaints in near work activities
Statistical Analysis: The paired t test was used in analyzing the results
ResultsOf the 87 screened subjects, only 70 were found eligible;
these were screened and 11(15%) were enrolled
Parameters Results
Female: Male 10:1
Average age 26.46 yrs (SD: 7.29; range: 19 to 45 yrs
Average MRSE RE -4.81 D (SD: 3.22)
Average MRSE LE - 4.76 D (SD: 2.93)
Mean Anisometropia 0.71 D (SD: 0.76)
All the deviations were exodeviations
Change in the deviation post operatively
0
5
10
15
20
25
30
distance deviation pre op 0 30 4 0 0 2 0 18 0 3 2
distance deviation post op 0 25 2 0 0 10 0 10 0 0 2
1 2 3 4 5 6 7 8 9 10 11
Pre op Post op
Distance 5.36 pd (SD: 9.69)
4.45 pd (SD: 7.84)
Near 7.45 pd (SD: 6.59)
4.90 pd (SD: 3.2)
P= 0.464
0
5
10
15
20
25
near deviation pre op 3 25 5 3 3 4 3 10 6 8 12
near deviation post op 3 8 2 3 0 5 4 10 5 4 10
1 2 3 4 5 6 7 8 9 10 11
P = 0.261
DiscussionApproximately 1.5 million LASIK being done every year - myopia - most
common diagnosis… it is important to anticipate and predict postoperative complications
In our study… phorias present in 15% of the patients who underwent refractive surgery
Although not statistically significant, there was a general trend towards an
overall improvement in the degree of deviation post operatively
Review of Literature But, there are multiple case reports of
diplopia/decompensation post refractive surgery !!!
On detailed review, all had risk factors:• Targeted monovision• Unilateral refractive surgery• Anisometropia • Amblyopia
- Kushner B J, Lionel Kowal. Diplopia after Refractive Surgery: Occurrence and Prevention. Arch Ophthalmol 2003; 12:315-321.Schuler E, Silverberg M, Beade P, Moadal K. Decompensated strabismus after laser in situ keratomilleusis. J Cataract Refract Surg 2000; 26: 1552-4.
Discussion Deviations preoperatively controlled with
deliberate myopic overcorrection or prisms in glasses - missed in the pre operative evaluation*
There was no such case in our series … ours was a controlled study with strict
inclusion and exclusion criteria
*Kushner B J, Lionel K. Diplopia after Refractive Surgery: Occurrence and Prevention. Arch Ophthalmol 2003; 12:315-321.
Discussion Strengths
Among the first prospective, controlled studies for myopes in the general population presenting for refractive surgery
Most reports to date have been isolated case reports that have been retrospectively reviewed once the decompensation settled in
Drawbacks
Cases with risk factors excluded
Larger prospective study needs to be planned
Conclusion
Refractive surgery for myopia does not
significantly alter the phoria state of the eye
Considering the increasing number of refractive surgeries being done, and the implications of missing a well controlled deviation pre operatively, orthoptics should be a part of pre operative work ups