In the repair of rhegmatogenous retinal detachment, identifying all causative breaks is a prerequisite for postoperative reattachment. However, breaks are not always visible preoperatively or intraoperatively in all cases.
The annual incidence of rhegmatogenous retinal detachment is 10–18 per 100,000 people. 20–40% occur after cataract surgery, and 10% are associated with trauma. 1) Earlier repair is associated with better reattachment success rates and visual prognosis. 1)
The relationship between lens status and difficulty in detecting breaks is as follows:
Several techniques have been developed to detect such occult breaks intraoperatively, and understanding the principles, indications, and success rates of each technique is required.
Optical scattering from the intraocular lens and posterior capsule opacification hinder observation of the peripheral fundus, resulting in a higher rate of detection difficulty than in phakic eyes. Additionally, lattice degeneration and postoperative inflammatory changes after cataract surgery also reduce visibility.
Scleral Depression
Principle: A depressor is applied from outside the sclera to dynamically observe the peripheral fundus.
Indications: Useful for detecting retinal breaks near the ora serrata. Applied as deep dynamic scleral depression during closed microsurgery.
Schlieren Phenomenon
Principle: Optical streak patterns that occur when liquids with different refractive indices mix. Observing during vitrectomy visualizes subretinal fluid (SRF) drainage from the break.
Indications: Cases of extensive rhegmatogenous retinal detachment where identifying the break site is difficult.
Cryopexy Test
Principle: Two rows of continuous cryopexy are applied from the ora serrata to the equator. The break is visualized as an immediate type (opacification within the ice ball) or a delayed type (pale gray change after a few minutes).
Indications: Identification of peripheral breaks. Break treatment with cryopexy or laser can also be performed simultaneously. 4)
Endoscopy
Principle: Observe from inside the eye using a fiberoptic endoscope as a light source.
Indications: Cases where scleral indentation is difficult (e.g., scleral staphyloma). Allows simultaneous vitreous base shaving and retinal break detection.
Deep dynamic scleral indentation during closed microsurgery is a fundamental technique useful for detecting retinal breaks near the ora serrata. It is positioned as a procedure supporting peripheral retinal examination during vitrectomy. 4)
In macular hole surgery, it is recommended to examine the peripheral retina with scleral indentation after inducing posterior vitreous detachment. 3) After removal of epiretinal membrane and internal limiting membrane, the presence of retinal breaks is also confirmed. 2)
Wide-angle viewing systems (Resight, BIOM, etc.) assist in searching for peripheral retinal breaks. 4)
The Schlieren phenomenon refers to optical inhomogeneities within a transparent medium. It is observed as characteristic “streak” patterns when liquids of different refractive indices mix. If this phenomenon is observed during vitrectomy, it indicates the site of SRF drainage, i.e., the presence of a retinal break.
There are two types of procedures that utilize the Schlieren phenomenon. A comparison of each method is shown below.
| Method | Material Used | Success Rate |
|---|---|---|
| Heavy liquid method (PFO) | Perfluorocarbon liquid such as C8F18 | 44% (11 of 25 eyes) |
| DE-TECH transretinal method | Trypan blue + 41G needle | 80–89% |
| DE-TECH transscleral method | Trypan blue + 30G needle | 80–89% |
This technique uses perfluorocarbon liquids such as C8F18 to drain subretinal fluid through the break and visualize it as a schlieren phenomenon. The reported success rate is only 11 out of 25 eyes (44%). 4)
This technique involves injecting dye (trypan blue; TB) into the subretinal space to enhance the contrast of the schlieren phenomenon caused by dye drainage.
Transretinal approach: TB is injected through a posterior retinotomy using a 41G needle. Then, under perfluorocarbon liquid (PFCL) tamponade, dynamic scleral depression is performed to observe dye drainage from the break.
Transscleral approach: A 30G needle is inserted into the most bullous (highly elevated) area to inject TB. Subsequent steps are the same as the transretinal approach.
The success rate is 80–89%, significantly higher than the heavy liquid method. A representative case report describes an 82-year-old male with total retinal detachment where a peripapillary break hidden by scleral staphyloma and retinal atrophy was identified using DE-TECH.
This technique involves applying two rows of continuous cryopexy from the ora serrata to the equator to visualize the break.
Since cryocoagulation itself also treats the tear, it has the advantage of allowing simultaneous detection and treatment. However, excessive cryocoagulation carries the risk of complications.
This technique uses a fiber-optic endoscope as a light source to directly observe the vitreous base from inside the eye.
Tears were identified in 19 of 20 cases (95%), and no complications were reported. The main advantages are as follows.
When a tear cannot be directly detected, buckling is performed on the quadrant where a tear is presumed to exist based on the detachment morphology (fluid distribution and elevation pattern). It is reported that 95% of primary tears are localized within this presumed area, and this approach is considered a last resort.
Perform scleral buckling in the quadrant where a break is suspected based on the detachment pattern. It is reported that 95% of primary breaks are located within that area, making this an effective strategy even when direct identification of the break is difficult.
Causes of latent breaks can be classified into optical/anatomical obstacles and localization issues.
| Classification | Factor | Specific Example |
|---|---|---|
| Anterior segment | Optical obstacles | Corneal opacity, small pupil, intraocular inflammation |
| Lens | Media opacity | Cataract, residual cortical fragments |
| Posterior segment | Vitreous disorders | Vitreous opacity, vitreous hemorrhage, fibrosis |
| Specific sites | Anatomical variations | Scleral staphyloma, microtears |
B-scan ultrasonography is used for preoperative evaluation, but its sensitivity for detecting retinal breaks ranges from 44% to 100%. 1) Wide-angle fundus photography cannot replace fundus examination. 1)
Trypan blue is widely used for various staining in vitreoretinal surgery, but if retained, it can cause retinal toxicity. After DE-TECH, thorough intraocular irrigation is required to remove the dye as much as possible.
Rhegmatogenous retinal detachment occurs when liquefied vitreous enters the subretinal space through a full-thickness retinal break (tear). 1)
Posterior vitreous detachment (PVD) results from separation of the posterior vitreous cortex from the internal limiting membrane (ILM). 1) It plays a central role in the pathogenesis of rhegmatogenous retinal detachment.
The natural course of retinal breaks and the effect of treatment intervention are as follows.
If surgery is completed without detecting a retinal break, it directly causes postoperative redetachment. Therefore, intraoperative identification of occult breaks is one of the most critical factors determining the success of retinal detachment repair.
For detected breaks, endolaser photocoagulation or cryocoagulation is performed to adhere the break edges to the fundus. In cryocoagulation testing, detection and treatment can proceed simultaneously. 4) Gas tamponade or scleral buckling is combined to achieve retinal reattachment.
