We are committed to a refractive surgical correction of presbyopia and exploring its postoperative visual acuity effect and coronal morphology in order to provide a reliable reference value for the clinical application of this technology. The correction technique applied in this paper has improved the phenomenon of insufficient distance vision and difficulty in adaptation after multifocal correction in the past, and is more suitable for patients with high requirements for distance vision. In the future, we will pay more attention to the comparative research of several different correction method and try to provide the best treatment plan for patients with presbyopia in different conditions.
To plan the monocular biospheric ablation profile, open the Imaris software. Select the anterior segment and corneal aberration analyzer with the aberration free mode for the dominant eye to eliminate aberrations and target refraction of zero. For the non-dominant eye, select the monocular by aspheric ablation profile with an optical zone of 6.2 to 6.7 millimeters.
Set the target to 0.89 diopters in the distal zone and introduce an ADD in the central three millimeter zone. After selecting the patient with a monocular by aspheric ablation profile, ask the patient to open their eyes and look upward. Rinse the conjunctiva sac with 0.9%normal saline.
Disinfect the skin around the eyelid center using a disinfectant. Place the patient supine with the head properly aligned. Drop artificial tears into the ocular surface to moisten it.
Lay the surgical towel and expose the surgical eye. Stick a transparent dressing frame. Open the eyelid fissure to fully expose the cornea and wipe the cornea with a wet sterile sponge.
Use the Femtosecond Laser system to create the corneal flap. Attach the negative pressure suction ring to the laser emission window and treatment control panel. Select the flap mode and start the treatment steps according to the program displayed on the screen.
Ask the patient to look at the green light. Using the operating microscope and joystick, align the watermark in the center of the contact lens on the negative pressure ring, ensuring it reaches about 80 to 90%Start the negative pressure suction until the cornea completely adheres to the contact surface of the negative pressure ring. Listen for section on to indicate the end of negative pressure suction and ready for the next step of preparation.
Depress the pedal connected to the laser to start the ablation process, and instruct the patient to focus on the green gaze light. After setting the corneal stromal flap parameter as mentioned, record the corneal ablation process. Upon completion of the corneal flap production, release the pedal, disengage the negative pressure suction and remove the suction ring.
Next, position the patient supine on an excimer laser surgical bed. Place the surgical towel and stick a transparent dressing frame around the patient's eye. Open the eyelid fissure to fully expose the cornea.
After rinsing the corneas with saline, align them using the operating microscope. Separate the corneal flap using a flap separator starting from the lateral incision near the hinge. Gently continue separating the flap from the stroma in the opposite direction of the pedicle until full opened, exposing the stroma.
Dry the stromal surface moisture, using a sterile medical sponge. Use the excimer laser to ablate the corneal stroma. After verifying the patient's information, perform the ablation according to the surgical design.
Ask the patient to stare at the gaze light while aligning the eyes with the laser and center the corneal apex to select for the stromal ablation. After treatment, rinse the stroma with a compound electrolyte intraocular irrigating solution. Reset the corneal flap.
Apply 0.3%tobramycin and dexamethasone eyedrops, and observe the corneal reset under a slit lamp. After correction of presbyopia, significant differences in uncorrected distance visual acuity between the dominant, non-dominant, and both eyes before and after surgery were observed. After surgery, the corneal asperity index of both dominant and non-dominant eyes was positively changed and the changes were statistically significant.
Both binocular spherical aberrations increased after surgery with a statistically significant increase in spherical aberrations in the dominant eye.
