Qualitative and Quantitative Endothelium Changes After Cataract Surgery: Ultrasound Phacoemulsification vs Nanolaser Technique
Condition: Effect of Cataract Surgery on Corneal Endothelium; About 2 Techniques
MeSH terms: Cataract; Capsule Opacification
Study type: Interventional

Summary: 
      Purpose: The aim of this study was to evaluate corneal endothelial cell density and
      morphology, central corneal thickness, and best visual acuity using US phacoemulsification or
      Nanosecond laser technique.

      Setting: Department of ophthalmology, Nabeul, Tunisia. Design: Prospective cohort study.
      Methods: The study included eyes with nuclear cataract density grade 1, 2, 3, or 4 according
      to LOCS III, divided into two groups; Group 1 had conventional US, and group 2 had nanosecond
      laser. The Endothelial Cell Density (ECD), coefficient of variation (CoV) in cell size,
      percentage of hexagonal cells, central corneal thickness and best visual acuity were
      evaluated over 24 months.
    

Detailed description: 
      Methods:

      A randomized prospective, uncontrolled cohort study was conducted at the Department of
      Ophthalmology of the Mohamed Taher Maamouri Hospital (MTMH) from March 2017 to May 2020. The
      MTMH ethics committee approved this study. All patients provided informed consent for the use
      of their data. The study adhered to all tenets of the declaration of Helsinki.

      All patients underwent complete ocular examination including visual acuity, clinical corneal
      assessment, intraocular pressure (IOP) measurement, and nuclear hardness grading based on the
      lens opacity classification system III (LOCS III), commonly referred to in most studies. Only
      the nuclear component of the cataract (NO1 to NO4) was taken into account in the evaluation.

      The endothelium of the central cornea was examined with a non-contact specular microscope
      (SM) (TOMEY CORP EM-4000).

      Patients were randomly divided into 2 groups. Group 1 had US PHACO using the phaco-chop
      technique (Stellaris PC: Bausch + Lomb®) and group 2 underwent an NL PHACO (Cetus A.R.C.
      Laser system®).

      The Cetus A.R.C. Laser system is composed of a base that generates a 4 to 5 ns pulsed Nd: YAG
      of 1064 nm wavelength laser with a pulse frequency up to 10 Hz and an optic fiber that
      transmits the laser pulses to the disposable single-use coaxial handpiece. The probe used has
      a total diameter of 720 µm, occupied in its center by a 320 µm quartz optical fiber that
      transferred the laser pulse towards a titanium plate in the phaco probe. The individual pulse
      energy ranged from 30 to 50 % of maximum power and the pulse frequency was 1-2 Hz.

      The base unit is connected to the same phaco aspiration/irrigation system and is controlled
      by the pedal of that system.

      In both groups, surgery started with a clear corneal incision of 2.2 mm at 9 o'clock and a
      port incision of 1 to 1.5 mm at 2 o'clock using the same knife. Continuous Circular
      Capsulorhexis (CCC) of 6 mm was performed under the same ophthalmic viscosurgical device (3%
      Sodium hyaluronate, 4% chondroitin sulfate, DuoVisc® Alcon ). A hydro dissection was
      performed, then followed by phacoemulsification.

      In-group 1 (horizontal phaco chop): after cortex aspiration, the nucleus was held with the
      phaco tip at a high vacuum. The phaco chopper was then introduced from the side port incision
      to engage, under the lower edge of CCC. It was then drawn towards the phaco tip to cleave it
      by a manual separation between the two instruments. The same process continued for the two
      nuclear halves and the fragments were then aspirated with phaco power. The standard
      parameters used during phacoemulsification were a vacuum level of 500 mmHg, pressurized
      irrigation of 90 mmHg, and 40% of phaco power. Energy was expressed in % on the PHACO machine
      and initially converted into Watts according to the following curve "Figure 1" then into
      Joules based on the formula: Energy (Joules) = Power (Watts) × time (seconds).

      In-group 2: The cortex and epinucleus were aspirated. The nucleus was fragmented using the
      shockwaves emanating from the phaco tip and then aspirated. The phaco chopper was used to
      accelerate the mechanical fragmentation of the nucleus and minimize the dissipated energy.
      The energy used was calculated automatically by the ARC Laser machine and was displayed on
      the screen.

      In both groups, after bimanual infusion/aspiration cortex removal and Visco expansion of the
      capsular bag, a hydrophobic single-piece: AcrySof acrylic (SA60AT, Alcon) IOL was implanted.
      The duration of the whole procedure (in minutes) was noted.

      Uncorrected Visual acuity (UVA) at 1 day postoperative and BCVA at 1 week, 1, 3, 6, and 24
      months after surgery as well as corneal edema and anterior chamber (AC ) reaction were
      recorded. A visual outcome of 0.5 logarithm of the minimal angle of resolution (logMar)
      without correction was considered a successful result based on the World Health Organization
      definition (1, 15, 16). The SM was performed at 1 week, 1, 3, 6, and 24 months after surgery.
      The investigators reported endothelial cell density (EDC) (cell/ mm²), the percentage of
      hexagonal cells, coefficient of variation (CoV) in cell size, and central corneal thickness
      (CCT) at each follow-up visit.

      All the data were analyzed using SPSS software (version 21.0; SPSS, Inc., Chicago, IL, USA).
      BCVA data was converted into log MAR for statistical analyses. Quantitative variables were
      presented as medians, means, and standard deviations. The investigators used Student's t-test
      for the independent series. Pearson's correlation coefficient was used for searching the
      statistical relationship or association between variables. A p-value < 0.05 was accepted as
      statistically significant.
    

Intervention name(s): phacoemulsification; utrasound phacoemulsification; nanolaser phacoemulsification
Intervention type(s): Procedure; Procedure; Procedure
Intervention description(s): we started with a clear corneal incision of 2.2 mm at 9 o'clock and a port incision of 1 at 2 o'clock. Continuous Circular Capsulorhexis of 6 mm was performed under the same ophthalmic viscosurgical device. A hydro dissection was performed, then followed by phacoemulsification.
the Nucleus has been treated using 2 different techniques After bimanual infusion/aspiration cortex removal and Visco expansion of the capsular bag, a hydrophobic single-piece: AcrySof acrylic IOL was implanted.; US group:The nucleus was held with the phaco tip at a high vacuum. The phaco choppe was drawn towards the phaco tip to cleave it by a manual separation between the two instruments. The fragments were then aspirated with phaco power. The standard parameters used during phacoemulsification were a vacuum level of 500 mmHg, pressurized irrigation of 90 mmHg, and 40% of phaco power; Laser group: The nucleus was fragmented using the shockwaves emanating from the phaco tip and then aspirated. The phaco chopper was used to accelerate the mechanical fragmentation of the nucleus and minimize the dissipated energy.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: A randomized prospective, uncontrolled cohort study
Masking: Single (Investigator)
Primary purpose: Treatment
Keywords: cataract surgery; phacoemulsification; Nanosecond laser; endothelial cells density