Part 1. The general principles and steps of vitrectomy for retinal detachment repair

- The 1t step of vitrectomy is cannulas insertion.

Three cannulas are usually placed: one for infusion, one for instruments like vitrector, forceps, etc., and one for the light.

Before opening infusion inside the eye, essential to check that infusion was placed into the vitreous cavity and not under the detached retina.

Depending on the case, more than three cannulas could be inserted.

- The 2d step is a core vitrectomy.

Core vitrectomy is debulking of the central part of the vitreous. This step is important for removing any vitreous tractions on the retina, allowing safe instruments insertion during the surgery, and creating the space for dyes injections.

- The 3d step is a posterior vitreous detachment.

- The optional step of the surgery is internal limiting membrane peeling.

It is believed that ILM peeling during retinal detachment repair prevents the formation of the postoperative macular epiretinal membrane. Important to note that studies that compared vitrectomy with and without ILM peeling for retinal detachment have reported controversial outcomes.

- The 4th step is a shaving of the vitreous base with scleral depression 360 degrees.

- The 5th step is subretinal fluid drainage and retinal flattening.

-The 6th step is endolaser.

After retinal reattachment endolaser should be done to create a barrier around the retinal breaks. Scarring of Laser burns allows chorioretinal adhesion only after around 2 weeks.

- The 7th step is endotamponade.

It is crucial in treating retinal detachment until the scars around the retinal breaks become stable.

• The final step is cannulas removal.

  Sclerotomies suturing is optional.

Part 2. Retinal Reattachment Techniques

- The 1t technique is fluid air exchange and simultaneous drainage of subretinal fluid through the retinal break without perfluorocarbon placement.

This technique is suitable for peripheral retinal detachment where a relatively small amount of subretinal fluid is present. Less suitable in the case of bullous retinal detachment, total retinal detachment, or detachment running through the fovea.

-The 2d technique to reattach the retina calls the “sandwich” technique.

In this case, the eye is filled with perflurocarbone to the most posterior retinal break border. Perflurocarbone facilitates the shifting of subretinal fluid from the posterior pole towards the retinal break. Then fluid-air exchange is performed while draining the subretinal fluid from the break. Once the retina is completely reattached, PFCL is removed and the endolaser is done under air.

-The 3d technique is filling the eye with PFCL up to the ora serrata.

In contrast to the previous techniques, in this case, the laser is performed under perflurocarbone liquid, which facilitates visualization of the retina. Before injecting the perflurocarbone essential to remove any traction over the retinal break that can resist retinal flattening, otherwise, PFCL can migrate to the subretinal space.

Part 3. Subretinal fluid drainage and flute needle

- The internal removal of subretinal fluid is possible through the preexisting retinal break or drainage retinotomy during a fluid-air exchange. Perflurocarbone liquid can assist in subretinal fluid drainage

- The cannula tip should be placed above the retinal tear to drain the fluid without causing retinal incarceration or traumatic hemorrhage. The eye can be tilted toward the break to facilitate gravity-related shifting of the fluid to the drainage area.

-A small amount of Subretinal fluid is not necessarily removed completely in a case when the retinal break can be treated by endolaser or cryopexy.

- Flute and Backflush flute needles are usually used to drain the subretinal fluid. The Backflush flute needle handle incorporates a silicon reservoir with a side port. Pressing on this reservoir cause safe backflushing of the fluid or incarcerated tissue. A regular flute needle has only the side port for fluid drainage.

- There are a few types of backflush flute needles: for passive drainage and active drainage.

- A flute needle for passive drainage works on the principle of the pressure gradient, thus to initiate passive drainage of fluid intraocular pressure should be raised significantly (~ 60MMHG). The difference between the intraocular pressure and the atmospheric pressure allows the fluid to exit from the side port when it's not closed by the finger. Closure of the exit port by the finger prevents flow from the eye.

-An active flute needle utilizes automated suction to aspirate fluid from the eye thus, in contrast to a passive flute needle, it does not depend on intraocular pressure. The active flute needle has a silicone tube connected to the aspiration line of the vitrector. Pressing the pedal of the vitrectomy system while closing the hole over the backflush reservoir creates a vacuum for aspiration. When a hole over the backflush reservoir is open or the pedal for aspiration is not pressed, there is no vacuum in the system thus, there is no aspiration. Important to know that an active flute needle can also be used as a passive one.

Part 4. Drainage retinotomy and diathermy

- Drainage retinotomy may be helpful in the following cases :

1. When the primary retinal break is not observed

2. When the primary break does not allow the drainage of most of the subretinal fluid (eg in long-standing retinal detachment where subretinal fluid becomes viscous)

3. To assist in the subretinal fluid removal from the posterior pole in the case where perflurocarbone liquid is not available or, for some reason, planned not to be used

- Diathermy is commonly used to perform drainage retinotomy. The benefits of the diathermy are that it makes coagulation so prevents bleeding, and also marks the borders of the retinal break thus, after retinal flattening, this area can be easily observed.

- Drainage retinotomy can also be done by a vitrector. However, in this case, retinotomy will be larger and after retinal flattening, it will be challenging to observe the border of the retinotomy for optimal SRF drainage.

- The location of drainage retinotomy should be optimal for removal of the fluid, to be as far as possible from the macula and as superior as possible to allow good closure with an endotamponade at the end of the case.

- Bipolar diathermy is used in intraocular vitreoretinal surgeries. In bipolar diathermy, the electrical radio frequencies generated between two electrodes on the instrument itself thus do not pass through the patient’s body and do not require the usage of the grounding plate.

Part 5. Endolaser in retinal detachment surgery

- In retinal detachment surgery endolaser photocoagulation is used to create scars around retinal tears, drainage retinotomy, or for treatment of suspicious areas without any identified breaks

- Some surgeons prefer intraoperative 360° prophylactic endolaser in every retinal detachment surgery.  But several studies showed that extensive laser treatment could affect pupil size by causing the injury of ciliary nerves

 - The choice of the laser technique depends on the surgeon's preferences and experience

General principles:

1. Laser in retinal detachment surgery is usually performed under air or perflurocarbone liquid after retinal reattachment. Adequate subretinal fluid aspiration allows the retinal pigment epithelium effectively absorb the laser energy for further scar formation.

2. Laser burns are generally done in a few rows peripherally or adjacent to the margins of the retinal defect.

3. The burn spot should be not too strong and not too large. The Laser is usually titrated to an observable retinal whitening. The size of the spot, the power, and the duration could be set in advance in the vitrectomy system and regulated depending on the case. The size and strength of the laser burn also depend on the distance of the laser tip from the retina. The closer the probe is to the retina, the smaller the size of the spot and the stronger the burn. The too strong Laser can cause retinal defects and bleeding.

4. The scleral indentation can assist with peripheral laser. Switching the laser probe with an infusion line in the inferior scleral canula can assist in performing laser in the superior part of the retina.

   - Several types of laser probes exist.

   The most common are:

   • Straight laser probe (allows easy insertion through the scleral canulas. This probe should be used with caution in phakic patients to avoid lens injury)

   • Curved laser probe (allows reducing the possibility of the lens trauma when reaching the contralateral side and far periphery. But this probe should be carefully inserted and removed through a scleral cannula because it can be accidentally pulled)

   • Laser probe with an extendible curved tip (combines benefits from both straight and curved laser probes. On the one hand, by releasing the handle, the probe goes back into a straight position and thus can be safely inserted and removed. On the other hand, the extendible curved tip allows laser even in the far periphery)

   • Illuminated laser probe ( has an optical fiber integrating lighting and laser abilities, therefore this probe eliminates dependency on the separate light pipe and allows surgeon-independent scleral depression for peripheral retinal breaks during the laser. But the illuminated laser probe provides a small field of view of the treated area. Therefore its usage can be challenging for surgeons who are not used to it)

Part 6. General principles of silicone oil injection

- Silicone oil can be used as an endotamponade in managing the following situations:

•  Complicated or recurrent retinal detachments

• An uncompliant patient who will not pose the head after the surgery or a patient who, for some reason, has difficulties with head posture

• A patient who planed to have high-altitude travel right after the surgery and cannot wait till the gas absorption

•  A patient with only one eye ( But here is a catch, on the one hand, after the surgery, silicone oil-induced refractive error can be corrected, allowing a patient to function even with silicone oil in the eye. On the other hand, it should be considered that a second surgery is required to remove the oil)

- Multiple techniques exist for silicone oil injection

•  Without direct visualization of the retina

• Under direct visualization of the retina

• The combination of both