Cataract Surgery Procedure

Alcon Centurion Vision System [12]
Alcon LenSx Cataract Femtosecond Laser [13]
Alcon LuxOR Surgical Microscope [14]

What is Cataract?

A cataract is a condition that the lens in the eye is clouded, causing blurry vision.

Cataract vs Normal Lens ©Blackrock Eye Care [20]

Sheri Rowen M.D. Cataract Surgeon NVISION Eye Centers [19]

Cataract Vision ©Cedar Park Vision [21]
Cataract Vision ©Eye Clinic P.C. [22]

What is Cataract Surgery?

Cataract Surgery is the removal of a clouded lens and injection of IOL (intraocular lens), a synthetic lens into the eye.

Types of Cataract Surgery

Cataract Surgery is broken down into 2 categories:
   1. Conventional Cataract Surgery
   2. Femtosecond laser-assisted cataract surgery (FLACS)

Cataract Surgery ©NPR [15]
Alcon Intraocular (IOL) Lens ©MyAlcon.com [17]
Intraocular Lens (IOL) ©Wikimedia.com [16]

Conventional vs Laser Assisted Cataract Surgery

Conventional cataract surgery uses a phaco (ultrasound) handpiece to perform Phacoemulsification, which is the breakage and aspiration of a cataract lens.  The procedure for laser cataract surgery is still the same as the conventional one but with additional steps.  The laser technology is used to make the main incision, additional incision, capsulorhexis, which is a removal of part of the anterior capsule membrane, and the fragmentation (pre-cut) of the lens prior to phacoemulsification to make breakage and aspiration of cataract lens with less energy and time.

Conventional Cataract Surgery

Conventional cataract surgery is broken down into the following steps.

1. Apply anesthesia to the eye
2. Main incision to allow phaco handpiece tip insertion
3. Additional incision to allow other tools to be inserted into the eye
4. Ophthalmic Viscosurgical Devices (OVD) injection
5. Capsulorhexis
6. Phacoemulsification
7. Capsule Polishing
8. IOL Injection
9. Irrigation and aspiration clean up

Femtosecond laser assisted cataract surgery (FLACS)

The laser or femtosecond laser cataract surgery sounds like a fancy way of working on cataract surgery. The femtosecond means 1×10-15 seconds.  The energy from the laser is applied for a very short period (femtosecond) and heats the surgical area to create the photo-disruption, a tiny disintegration of tissue.  The machine repeats this step in the neighboring area, resulting to create a separation of tissue.  The overall process is generally the same as the conventional procedure and it uses the laser to automate the process of

Step 2. Main incision to allow phaco handpiece tip insertion
Step 3. Additional incision to allow other tools to be inserted into the eye
Step 5. Capsulorhexis
Step 6. Phacoemulsification: the laser makes a pre-cut on the lens prior to phacoemulsification

photodisruption [9]

It is a computer-aided process, therefore, it makes almost perfect centration of the capsulotomy, meaning it removes the anterior capsule membrane accurately and quickly. It also makes pre-cut on the cataract lens very quickly without making physical contact. This makes the phacoemulsification process much faster. The overall laser process takes about 2 minutes. Alcon’s LenSx laser produces 51% less phaco time and 43% less phaco energy [3].

What is Femtosecond Laser?

A femtosecond (FS) laser is an infrared laser with a wavelength of 1053nm [18].  The visible range of wavelength is about 380 nm to 700 nm.  The energy from the laser generates a rapidly expanding cloud of free electrons and ionized molecules [18], separating the surrounding tissues.  The electromagnetic wave is aimed at the intended surgical area.  The femtosecond laser for cataract surgery is only converged at the intended surgical area.  Therefore, the light penetrates and it doesn’t hurt the other area.

What are the benefits of Femtosecond laser-assisted cataract surgery?

  1. less phacoemulsification time and energy
  2. Accurate main and additional incision
  3. Clean circular cut of Capsulorhexis

What are the risks of Femtosecond laser assisted cataract surgery?

The same risks of conventional cataract surgery apply to the laser-assisted cataract surgery.  The femtosecond laser cataract surgery procedure does not yield superior results compared to conventional cataract surgery. The laser cataract does not result in fewer complications. It also does not provide a better outcome according to the article on AAO, American Academy of Ophthalmology [4]. The healing time after surgery is also the same.  The drawback and some of the risks are

  1. Increased cost
  2. Intraoperative capsular complications
  3. Risk of intraoperative miosis
  4. Dry eye
  5. Swelling of the retina

The femtosecond laser equipment costs north of $100,000. The additional cost is passed on to the patient. This study noted the risks of femtosecond laser-assisted cataract surgery-specific intraoperative capsular complications and intraoperative miosis [5]. The meta-analysis comparison for safety between conventional and laser-assisted procedures yielded that there are no significant differences between conventional cataract surgery and FLACS (femtosecond laser-assisted cataract surgery) for intraoperative capsular complications [8]. Some red eye complications and swelling of the retina are indicated in the two studies [6][7].  It largely depends on the skills of the surgeon.

Intraoperative miosis:
The excessive constriction and dilatation of the pupil during the surgery.

Intraoperative capsular complications:
The complication or damage to the posterior capsule area such as Posterior Capsule Rupture/Vitreous loss or damage to another part of the capsular bag.

Components of Eye

©ZEISS Medical Technology (International)
©ZEISS Medical Technology (International)

Conventional Cataract Surgery Procedure

1. Applying anesthesia to the eye

The anesthesia for cataract surgery is local and very minimal. The eye drop-like solution is applied to the surface of the eye or injected into the eye. The patient is awake and can communicate with the surgeon.

©ZEISS Medical Technology (International)

2. Main incision

The main incision is made on the junction between cornea and sclera for phacoemulsification (ultrasound) handpiece tip insertion. It’s about a 1.8 mm – 2.5 mm incision with a slit knife.

©ZEISS Medical Technology (International)

3. Additional incision

One or two additional incisions are made at the different locations on the junction between the cornea and sclera to allow knives or blade insertion during the phacoemulsification.

©ZEISS Medical Technology (International)

4. Ophthalmic Viscosurgical Devices (OVD) injection

The viscoelastic fluid, which is a high viscosity fluid is injected into the anterior chamber to protect the non-surgical area during the surgery. Now it’s ready for surgical procedure.

©ZEISS Medical Technology (International)

5. Capsulorhexis

The Capsulorhexis is a peeling of part of the anterior capsule surface to allow access to the cataract lens. The hook-shaped knife is used to scratch and peel the membrane of the anterior capsule. It makes an approximately 4.0 mm – 5.5 mm diameter cut.

©ZEISS Medical Technology (International)

6. Phacoemulsification

Phacoemulsification or simply “phaco” is a process of removing a cataract lens using a phaco (ultrasound) handpiece. The reason it’s called ultrasound is the tip of the handpiece oscillates above the audible sound frequency (20 – 20,000 Hz). It oscillates longitudinally (back and forth) or torsionally (left and right) depending on the surgeon’s preference. The oscillation helps to break the cataract lens and the aspiration line vacuums the fragments of the cataract lens.  Many surgeons prefer to use torsional. During the surgery, the surgeon typically keeps around 50% or less of maximum power. If the power is too high, the risk of inadvertently damaging the non-surgical area increases. If it’s too low, it takes more effort to remove the cataract lens. The phaco handpiece provides constant irrigation of BSS (balanced salt solution) which is a Sterile Intraocular Irrigating Solution and aspiration. The surgical area is constantly lubricated and cleaned with proper IOP (intraocular pressure).

The zonular fibers, which hold the original lens and the posterior capsule are intact and only the anterior membrane of the capsule of the capsular bag is removed during the cataract surgery. The patient still can maintain the function of focusing vision after surgery just like the biological lens.

©ZEISS Medical Technology (International)

Phacoemulsification [10]

7. Capsule Polishing

Capsule Polishing is the process of removing the remaining lens’ epithelial cells left on the surface of the capsule.  The remained epithelial cells can cause Posterior Capsule Opacification weeks, months, or years after cataract surgery.  The symptom is blurring vision similar to cataracts.  The polishing minimizes the risk of leaving epithelial cells.  To treat Posterior Capsule Opacification, posterior capsulotomy is performed.  The machine emits the laser to the posterior capsule surface to make a hole in the clouded part of the posterior capsule surface.

8. IOL Injection

The IOL (intraocular lens), which is a synthetic lens is injected by either a manually actuated or automated IOL injector into where the cataract lens was. IOL Lens comes with a variety of diopter, which is a thickness or the radius of the curvature of the lens surface. The higher the diopter, the thicker the lens or smaller the radius of the curvature. Typically, the diopter ranges from 10 to 33. The ophthalmologist will diagnose the patient’s vision and select the lens with optimal diopter, therefore, the patient won’t need a contact lens or glasses after cataract surgery.

©ZEISS Medical Technology (International)

IOL Injection [11]

9. Clean up

The cataract surgeon uses I/A (irrigation and aspiration) handpiece to remove any remaining debris in the eye. The I/A handpiece is a device that provides irrigation and aspiration of fluids without ultrasound motion. An I/A handpiece is used during any time of surgery to clean the surgical area.

Summery

The safety and recovery of cataract surgery largely depend on the skills of cataract surgeons for both conventional and laser-assisted cataract surgery. The femtosecond laser-assisted cataract surgery reduces the operating time and phacoemulsification energy. But it does not provide superior benefit to the patient and the increased cost of operation is passed on to the patient.

References

1. Cataract Surgery Animation
ZEISS Medical Technology (International)

2. LenSx Laser for Cataract Surgery at Harvard Eye
Harvardeye

3.  Alcon LenSx Femtosecond Laser System
Alcon Professional

4. Traditional Cataract Surgery vs. Laser-Assisted Cataract Surgery
Kierstan Boyd, Reviewed By J Kevin McKinney MD, Edited By David Turbert, Apr. 19, 2021
American Academy of Ophthalmology

5. The benefits and drawbacks of femtosecond laser-assisted cataract surgery
Review Eur J Ophthalmol. 2021 May;31(3):1021-1030. doi: 10.1177/1120672120922448. Epub 2020 Jun 7.
Piotr Kanclerz, Jorge L Alio
PMID: 32508179 DOI: 10.1177/1120672120922448

6. Evaluation of dry eye after femtosecond laser-assisted cataract surgery
J Cataract Refract Surg. 2015 Dec;41(12):2614-23. doi: 10.1016/j.jcrs.2015.06.036.
Yinhui Yu, Huixia Hua, Menghan Wu, Yibo Yu, Wangshu Yu, Kairan Lai, Ke Yao
PMID: 26796442 DOI: 10.1016/j.jcrs.2015.06.036

7. Cystoid macular edema after femtosecond laser-assisted versus phacoemulsification cataract surgery
J Cataract Refract Surg. 2015 Nov;41(11):2373-8. doi: 10.1016/j.jcrs.2015.04.031.
Shaun Y P Ewe, Carmen L Oakley, Robin G Abell, Penelope L Allen, Brendan J Vote
PMID: 26703485 DOI: 10.1016/j.jcrs.2015.04.031

8. Meta-analysis Safety of femtosecond laser-assisted cataract surgery versus conventional phacoemulsification for cataract: A meta-analysis and systematic review
Advances in Ophthalmology Practice and Research Volume 2, Issue 1, May–June 2022, 100027 Advances in Ophthalmology Practice and Research
Jingjie Xu, Xinyi Chen, Hanle Wang, Ke Yao

9. Current Progress in Femtosecond Laser-Assisted Endothelial Keratoplasty June 2013
In book: Femtosecond Lasers: New Research (pp.297-312)Chapter: 10Publisher: Nova Science PublishersEditors: Yuwen Zhang
Project: Biological inlays to alter corneal biomechanics and refractive properties
Andri Riau; Jodhbir Singh Mehta

10. Fluidics of the Alcon Centurion Cataract Surgery System
Matthew Rauen, MD

11. Using the AutoSert IOL Injector
Alcon Laboratories, Inc., Donald N. Serafano MD

12. About Alcon

13 . Alcon LenSx® Femtosecond Laser System
Alcon Professional

14. LuxOR® Revalia™ Ophthalmic Microscope
MyAlcon Professional

15. Anthem Says Eye Surgeons Should Monitor Cataract Anesthesia Themselves
February 20, 2018
NPR

16. Intraocular Lens
Wikimedia.com

17. Alcon Cataract IOL Options for Eye Care Professionals
MyAlcon.com

18. Femtosecond Lasers and Laser Assisted in Situ Keratomileusis (LASIK)
Manik Goel, MD, Shruti Aggarwal, MD, Vandana Reddy, MD
EyeWiki, Americal Academy of Ophthalmology

19. Cataract Surgery Demonstration with NVISION® Eye Centers Surgeon Dr. Sheri Rowen
NVISION Eye Centers – Corporate Office

20. Cataracts
Blackrock Eye Care

21. Cataract Surgery & Removal
Cedar Park Vision

22. Cataract Surgery In Portland OR
Eye Clinic P.C.