1. Mostafa Hamed Nabih MD, PhD Khaled G Abueleinen MD, PhD &FRCS (ed) Faculty of Medicine Cairo University EGYPT

2. Introduction Adherent posterior hyaloid an intraoperative challenge & cause of recurrent retinal detachment even in siliconized eyes. Hydrodissection is well known technique in phacoemulsification, but was not previously described for PH separation during vitrectomy. The aim of this study is to assess hydrodissection as an adjuvant method in separation of triamcinolone tinted posterior hyaloid.

3. Patients and methods 97 eyes with advanced or recurrent non diabetic rhegmatogenous RD. Triamcinolone acetonide (TA) was injected to enhance PH. Separation of the PH was tried, initially, with the suction of the vitrectomy machine. Non hydrodissection group:41 eyes. Hydrodissection group:56 eyes,divided into 2 subgroups: Non touch technique subgroup included 24 eyes. Touch technique subgroup included 32 eyes.

4. Results Successful separation of PH was achieved in 41.5%, 75% and 71.9% of eyes using non- hydrodissection, hydrodissection non- touch and touch techniques respectively (Chi-Square, P= 0.007). Those with successful separation were significantly older – median age 26 Y- than those without separation – median age 21 Y-(Mann-Whitney Test: P= 0.002)

5. Hydrodissection techniques induced less iatrogenic breaks and less retinal bleeding than non-hydrodissection (Chi-Square, P= 0.013 and P=0.001 respectively). However, there was no statistically significant difference in achieving primary or final success among the three techniques. (Chi-Square, P= 0.598 and 0.230 respectively).

6. Discussion Active suction and triamcinolone assisted dissection using vitrectomy forceps increased the success of vitrectomy and reduced recurrence. Hydrodissection, although well known in cataract surgery, it has not been described previously as a method of separation of adherent posterior hyaloid.

7. Compared to previous techniques, hydrodissection is easy with fewer complications. Further assessment of this technique on large sample is going on to obtain more significant data.

8. Conclusion Hydrodissection could be an effective adjuvant to separate the posterior hyaloid. Also, it can reduce the incidence of iatrogenic breaks and intraoperative bleeding. The non touch technique could be safer with lower risk of iatrogenic breaks.