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Novel Intraop keratoscope-guided penetrating keratoplasty with realtime suture adjustment to control astigmatism.

Introduction :

Even though achieving a clear graft after a meticulous surgery is considered as a successful keratoplasty, if  associated with high astigmatism it may delay or prevent good visual recovery. Graft host size disparity, suturing techniques and healing process may give rise to unpredictable astigmatism[1].Many techniques have been described to reduce postoperative astigmatism mainly based on suturing technique and its removal.

In 1977, Mcneill et al described a method of using double running nylon sutures. But removal of one continuous suture was associated with unexpected changes in astigmatism[2]

In 1982, Stainer described a method to use combination of continuous and interrupted sutures. This provides facility for selective interrupted suture removal to correct astigmatism[3]

In 1995, Serdarevic et al for the first time showed that intraoperative adjustment of sutures  facilitated early visual rehabilitation, safety and refractive stability[4].

In 2007, Vinciguerra et al concluded that a combination of  intraoperative  topography  based adjustment with single running suture resulted in mean refractive astigmatism of 3.53D in a sample of 165 eyes[5].

None of the above techniques facilitates real-time intraoperative suture adjustment. Though topography is used, it needs to acquire multiple images multiple times, and there is always a chance to over tighten or loosen the suture as it is done between image acquisition.

Technique: Considering these drawbacks we designed an innovative microscope attachable keratoscope which was used while suturing. Cornea was moistened with balanced salt solution and excess fluid was removed with a methylcellulose sponge to obtain a clear undistorted reflection from the keratoscope ring (THE DESCRIPTION OF THE DEVICE,KERATOPLASTY PROCEDURE, SURURING TECHNIQUES, POSTOPERATIVE OUTTCOMES, COMPLICATIONS, GRAFT REJECTION IS LACKING). Based on the shape of reflection, suture is loosened or tightened to obtain a circular reflection. (DESCRIBE INTRAOP SUTURE ADJUSTMENT)

Figure 1: Keratoscope ring can be seen attached at the objective of microscope.

Figure 2:  Distortion of reflection as a peaking at 5 o clock position.

Figure 3: By adjusting the tightness of suture a circular reflection is obtained.

Materials and Methods : 100 eyes of hundred patients were included in this retrospective study. 50 eyes with intraop keratoscope use (group A) and 50 eyes without  intraop keratoscope use (group B)  were included (PATIENT DEMOGRAPHICS, INDICATIONS OF KERATOPLASTY, ADDITIONAL

PROCEDURES IF ANY, STUDY DURATION, FOLLOW UP lacking). Post operative Mean refraction (MRA),  topographical astigmatism(MTA), uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA) at 1 year followup are recorded and analysed.

THERE IS NO IN-TEXT MENTION OF TABLES AND FIGURES.THERE IS NO STATISTICAL ANALYSIS

Results :

DESCRIPTION OF TABLES IS LACKING.

Results: At 12 months postoperative period (suture out) the MRA was 1.38 D and MTA was 2.46 D in group A. The MRA was 4.34 D and MTA was 5.34 in group B. Mean UCVA and BCVA was 0.3(6/12) (??? 6/12 is 0.5) & 0.1(6/7.5) ????? (0.1 is 6/60) in group A, 0.8(6/38) & 0.3 (6/12) respectively in grp B.

Conclusion :  CONCLUSION COMES AFTER DISCUSSION. The new intraop keratoscope is an effective device in controlling postoperative astigmatism. The mean BCVA of 0.1 was achieved immediate postop and maintained. Visual rehabilitation time & need for further intervention to correct astigmatism is reduced. (MENTION REHABILITATION TIME AND WHAT ADDITIONAL PROCEDURES WERE UNDERTAKEN)

Discussion: Penetrating keratoplasty has evolved into a highly successful transplantation procedure, with graft clarity rates in keratoconus patients reaching levels as high as 97% at 4 years postoperatively[8]. However, postkeratoplasty astigmatism remains the major impediment for achieving satisfactory visual rehabilitation in these patients[1] . Cases of astigmatism as high

as 20 D have been reported[9,10]

Postoperative suture adjustment is recognized as a safe procedure with a significant clinical and statistical effect on immediate astigmatism correction but can be unpredictable. With this in mind, we reasoned that suture adjustment during suturing  using an intraoperative keratoscope, may give better postkeratoplasty astigmatism results than adjustment at a later stage of the follow-up period. The working hypothesis was that intraoperative adjustment was preferable to a later adjustment when significant scarring had already taken place and a high astigmatism was already established. Our results show that the use of intraoperative keratoscope guided suture adjustment is feasible and that it enables a faster recovery of BCVA and good astigmatism results as early as the first postoperative month.

References :

  1. Sebai Sarhan AR, Dua HS, Beach M. Effect of disagreement between refractive, keratometric, and topographic determination of astigmatic axis on suture removal after penetrating keratoplasty. Br J Ophthalmol. 2000;84:837–841.
  2. McNeill JI, Kaufman HE. A double running suture technique for keratoplasty: earlier visual rehabilitation. Ophthalmic Surg. 1977;8:58–61.
  3. Stainer GA, Perl T, Binder PS. Controlled reduction of postkeratoplasty astigmatism. Ophthalmology. 1982;89:668–676.
  4. Binder PS. Selective suture removal can reduce postkeratoplasty astigmatism. Ophthalmology. 1985;92:1412–1416.
  5. McNeill JI, Wessels IF. Adjustment of single continuous suture to control astigmatism after penetrating keratoplasty. Refract Corneal Surg. 1989;5:216–223.
  6. Serdarevic ON, Renard GJ, Pouliquen Y. Randomized clinical trial of penetrating keratoplasty. Before and after suture removal comparison of intraoperative and postoperative suture adjustment. Ophthalmology. 1995;102:1497–1503.
  7. McNeill JI, Aaen VJ. Long-term results of single continuous sutureadjustment to reduce penetrating keratoplasty astigmatism. Cornea. 1999;18:19–2
  8. Brahma A, Ennis F, Harper R, et al. Visual function after penetrating keratoplasty for keratoconus: a prospective longitudinal evaluation. Br J Ophthalmol. 2000;84:60–66.
  9. Van Meter WS, Gussler JR, Soloman KD, et al. Post-keratoplasty astigmatism control. Single continuous suture adjustment vs selective interrupted suture removal. Ophthalmology. 1991;98:177–183.
  10. Nabors G, Vander Zwaag R, Van Meter WS, et al. Suture adjustment for postkeratoplasty astigmatism. J Cataract Refract Surg. 1991;17:547–550.

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