FP1769 : Outcome of Minimally Invasive Partial Tenotomy in small angle strabismus with Diplopia

Dr.Leila Mohan , Dr.PADMAJA KRISHNAN,Dr. K. AMACHANDRA BHAT

Abstract

Frustrating diplopia after a surgery for of strabismus or following trauma is not uncommon.Other than functional asthenopia or diplopia, cosmesis is not a problem in these patients. For fear of inducing an over or undercorrection,they are not operated.Prisms are not tolerated or not acceptable.Central Minitenotomy and graded partial tenotomy under topical anaesthesia are useful in these situations.Purpose:To see the outcome after partial tenotomy in small angle strabismus with diplopia.Methods:A retrospective analysis of 7patients who had surgery had pre and postoperative muscle balance evaluation with a follow up for 6m.Results:7cases,5 with hypertropia,4 following large horizontal XT correction, 1 after IOAT for superior oblique palsy- 2 consecutive esotropia.Mean PBCT was 8prisms(6-15)which reduced to 3pd(0-6)following partial tenotomy of SR in hypertropia and MR in ET.All had immediate relief of diplopia, 3 recurred and needed 2nd procedureConclusion:Minitenotomy/topical is a satisfactory procedure .

Introduction

Small angle strabismus may occur following surgery for large angle strabismus, traumatic paralytic strabismus after recovery from paralysis or decompensated congenital strabismus.It is most frustrating when a large angle horizontal strabismus has been fully corrected, but he comes again and again with complaints of troublesome vertical diplopia. Since the vertical fusional amplitude and  negativefusional amplitudes or divergence amplitudes  are much less(2to 4pd) than convergence amplitude(25 to 30 pd) any small vertical or eso deviation produces troublesome diplopia. In such cases cosmesis is often not the issue.Prisms as advocated traditionally is not universally acceptable due to either the optical aberrations, distortions  or its weight. A routine recess – resection procedure can lead to overcorrection and it is not easy to convince  another surgery. Here a short, noninvasive procedures is a satisfactory procedure, which can be repeated if necessary.

Graded verticalrectus tenotomy(GRVT) as an office procedure under topical anaesthesia, was proposed by Alan B Scott in 2000 to correct vertical diplopia.This involved repeated tenotomy of the muscle at its insertion by doing prism cover test until no diplopia and no movement is seen. Later Kenneth Wright proposed central mini tenotomy, a transconjunctivaltenotomy of the central third of the muscle at its insertion. Both procedures can be done under topical anaesthesia.

Purpose was to see the outcome  of noninvasive partial tenotomy at the insertion under topical  anaesthesia on small angle strabismus, with troublesome diplopia.

Material and Methods.

This study was done with the approval of the hospital ethics committee.It was a retrospective analysis of 7 patients who underwent partial tenotomy for diplopia. They had full ophthalmic evaluation including pre and postoperative assessment of diplopia and prism bar cover test(PBCT).

Results:

There were 7 cases,5 males and 2 females  age ranging from 16 years to 49 years with a mean age of 31years.5 had  hypertropia,4 following large horizontal XT correction, 1 after inferior oblique anterior transpositioning procedure for a decompensated congenital  superior oblique palsy’Two cases were  consecutive esotropia following 3 muscle surgery for large angle exotropia..Mean PBCT was 8.5prisms(6-15)which reduced to 2.6pd(0-6)following partial tenotomy of SR in hypertropia and MR in ET at the end of 3 months.All of them had relief of diplopia following surgery but later diplopia  recurred.in 3 .A second similar procedure was done in the opposite eye, the IR tenotomy done in hypertropia and MR in ET.All were relieved of diplopia at the end of 3months

The following is thechart of patients operated

No	name	age	se	diagnosis	preop de.	MiniT pro	postop de	diplopia	2nd sx	3m	6m
1	Muba	23	M	postLRR	R/L8pd	RSR miniT4	2d	nil	n	0
2	Fath	16	F	postLRR	RET10pd	bil MR mini	2pd	nil	n	4pd
3	Moh	21	M	post LRR	R/L8pd	RSR T	4pd	nil	n	4pd
4	Shobha	35	F	postLMR	LET15pd	LMR T	4pd	present	RMR T	6pd
5	Jose	36	M	postLRR	R/L8pd	RSR T	5pd	present	LIR T	2pd
6	biju	40	M	post IOAT	R/L5pd	RSR T	2pd	nil	n	0
7	joseph	49	M	post LRR	L/R6pd	LSR T	4pd	present	RIR T	2pd
		31.42857

Procedure

For GRVT,the patient had a thorough  PBCT done before surgery and after draping, topical anaesthesia applied, patient asked to look down maximally downward for SR partial tenotomy. After making a small conjunctival opening temporal to the insertion of superior rectus the insertion is grasped with forceps and lifted up with a small hook and about 60% temporal tenotomydone.Patient is made to sit up and PBCT repeated. If there was residual movement, the procedure is repeated.

For central minitenotomy , after blanching the conjunctiva with alphagan, the Central 30 to 40 % pf the MR insertion is grasped in the forceps, patient looking to opposite side..Avoid the vessels.Tenotomy is done through the conjunctiva.No suturing done.

Discussion

Diplopia is troublesome even in small deviations in vertical and esodeviations.When routine surgery is not feasible, tenotomy at the insertion under topical anaesthesia is a good alternative Repeatability is a big advantage. Tenotomy done at its insertion is the best.

Conclusion

Partial graded vertical rectus muscle tenotomy at its insertion gives good results in small hypertropiaproducingdiplopia.In troublesome small angle ET, centraltenotomy of MR gives good results.

Videos of the procedure will be shown during presentation

References

1. Mini-Tenotomy Procedure to Correct Diplopia Associated with Small-Angle Strabismus: Kenneth W. Wright MD^*:Trans Am OphthalmolSoc 2009 Dec; 107: 97–10.:
2. Graded vertical rectus tenotomy for small-angle cyclovertical strabismus in sagging eye syndrome:ZiaChaudhuri,Joseph L Demer:Clinical science
3. Central tenotomy for small angle deviation: Adele Marie M. Roa:JAAPOSFebruary 2010 :Volume 14, Issue 1, Page e25
4. Paediatric Ophthalmology and Strabismu:edited by Kenneth W. Wright, MD, et alWhat is new in PaediatricOphthalmology?IJO:Pradeep Sharma et al: 2017:6 : 3: 184-