In recent decade, a major improvement in vitreoretinal surgery was the use of small gauge surgical systems that improved the safety of vitrectomy and also reduced the surgical time. However, there were still some concerns regarding small gauge vitrectomy system, especially 27-gauge system, in the stability of its instruments and the efficacy of removing vitreous during surgery. Although there were some studies that had reported the surgical outcomes of 27G vitrectomy system, none had focused on patients with high myopia. The highly myopic patients usually had thinner sclera, which was a risk factor for wound leakage after sutureless vitrectomy, they also had longer axial length which would make the surgical procedure more difficult especially in macular surgery.

Based on previous clinical finding, gas leakage was 36.4% in 25G , while 27G sclerotomy showing less leakage comparing to larger gauge sclerotomy, the investigators believe 27G may have its clinical advantages in overcoming the thinner sclera of high myopia, and show the superiority of leakage control.

Hypothesis:

The 27G vitrectomy system has lower sclerotomy wound leakage rate compared with 25G system

Inclusion criteria:

1. Highly myopic patients (axial length 26~31mm)
2. Diagnosed with vitreoretinal pathology that require vitrectomy
3. Never received vitrectomy before

Exclusion criteria:

1. Surgical planning including scleral buckling during operation
2. Surgical planning including combined phacoemulsification
3. Surgical planning including the use of silicone oil and/or perfluorocarbon liquid
4. Previous ocular surgery involving conjunctival manipulation and scarring such as pterygium removal/trabeculectomy
5. Previous vitrectomy
6. Previous ocular trauma involving corneal/corneoscleral/scleral/conjunctival full thickness laceration
7. Medical history with known connective tissue disease(s)
8. Age younger than 20 years old