Correlation Between Sulcus Anatomy and Other Parameters After Horizontal & Vertical Intraocular Lens (IOLs) Placements
Condition: Cataract; Pseudophakia
MeSH terms: Cataract; Pseudophakia
Study type: Interventional

Summary: 
      Usually following cataract surgery patients would expect to have normal distance vision and
      not require the use of distance glasses. However, in clinical practice desired vision post
      cataract surgery is not achieved sometimes. In such cases a piggyback lens is used to enhance
      the visual outcome. This lens is placed in the ciliary sulcus (space between the iris and the
      lens). Often this piggyback lens is not the best fit for the ciliary sulcus space and it
      moves. This study will be using ultrasound biomicroscopy to measure the ciliary sulcus
      dimensions pre and postoperatively to estimate the normal anatomy and it's variations.
      Patients in this study will be randomised as to which way the intraocular lens is placed in
      the eye (horizontally or vertically) at the time of their cataract surgery. Patients
      requiring cataract surgery in both eyes will be identified from the Eye Hospital at the Royal
      Sussex County Hospital. Patients will be in the study for up to 6 months from being
      identified as suitable through to the operation in the 2nd eye and a final study visit.
    

Detailed description: 
      Study Design This is a prospective, fellow eye randomised study.

      Recruitment

      A sample size of 92 eyes (46 patients) was calculated. Patients will be recruited at the
      Sussex Eye Hospital preoperative cataract assessment clinics where they will be screened and
      given a patient information sheet by a member of the research team if they can be recruited.
      They will be allowed to take this home to discuss with their family/friends and/or GP. They
      will be asked if the research team could contact them in a weeks time to discuss the study
      and the plan for the day of their surgery (which is their next NHS visit). Patients can then
      agree or decline to participate in the study . If they decline, their normal NHS pathway will
      continue. If they accept, written informed consent will be taken on the day of surgery as
      well as any extra imaging required. The key points of the trial will be reiterated and the
      patient will be invited to ask any questions. All members of the research team are NIHR GCP
      trained. All research patients will undergo surgery by the same surgeon and attend for
      post-operative follow-up at the Sussex Eye Hospital. In addition at this visit a research
      appointment will be made to undertake the research scans and examinations (see details below)
      by an experienced member of our research team. The research team including the surgeon cannot
      be blinded as the obvious direction of placement of the intraocular lens will be visible
      during surgery and during examination.

      Pre-operative appointment

      Consent If the patient would like to participate they will be asked to read and sign a
      consent form. If the patient gives consent for their GP to be notified of their participation
      in the study a letter will be sent to the GP.

      Standard pre-operative protocol for all NHS patients:

        1. Unaided and best corrected distance visual acuity

        2. Intraocular pressure measurement (applanation tonometry)

        3. Optical or ultrasound biometry for lens power calculation

        4. Slit lamp examination of the eye (by a doctor) including dilated fundus evaluation For
           non-standard (research) measurements, patients will be asked to return for a separate
           appointment. All measurements will be performed at ambient room light (undilated pupil).

      The assessment will continue as follows:

        1. Scheimpflug scans (Pentacam)

        2. Anaesthesia of the eye with proxymetacaine 1%

        3. Measurement using digital calipers of the white-to-white diameter Carbomer gel will be
           applied to protect the cornea before application of ultrasound probe

        4. Contact ultrasound biomicroscopy images will be taken in 4 axes: vertical, horizontal,
           temporal oblique and nasal oblique. The patient will be asked to fixate with the fellow
           eye on a target to maintain fixation and avoid accommodation. The examination will be
           performed with undilated pupils.

      Surgery

      All surgery will be carried out by the same surgeon (Principal Investigator) who is an
      experienced senior Ophthalmic Surgeon. This is to avoid any surgery-induced study biases.
      Surgery will be performed employing a standardized technique with aspheric monofocal
      intraocular lenses. The eyes will be randomized (1:1) using a dedicated computer programme
      prior to the start of the study to have a vertical or horizontal placement of the intraocular
      lens in the capsular bag. The 0 and 180 degrees will be marked on the slit lamp prior to the
      surgery. The axes of the IOL will be orientated in reference to the midpoint of the optic
      haptic junction of the IOL.

      Non-standard (research)intervention post-operatively on the day of surgery:

      Image taken with anterior segment ocular coherence tomography.

      Standard post-operative protocol for all NHS patients at 4-6 weeks:

      1) Unaided and best corrected distance visual acuity 2) Intraocular pressure measurement
      (applanation tonometry) 3) Slit lamp examination of the eye Non-standard (research)
      post-operative measurements for patients enrolled in this study (performed at the time
      convenient to patient and the research team): All measurements will be performed at ambient
      room light (undilated pupil).

        1. Dilated retroillumination images of the IOL immediately postoperatively (ideally on the
           day of the surgery)

        2. Scheimpflug scans (Pentacam®) at 4-6 weeks

        3. Anaesthesia of the eye with proxymetacaine 1% at 4-6 weeks

        4. Carbomer gel will be applied to protect the cornea before application of ultrasound
           probe. The patient will be asked to fixate with the fellow eye on a target to maintain
           fixation and avoid accommodation. This examination performed with undilated pupils at
           4-6 weeks.

        5. Contact ultrasound biomicroscopy images at 4-6 weeks will be taken in 4 axes: vertical,
           horizontal, temporal oblique and nasal oblique.
    

Intervention name(s): Horizontal placement of the intraocular lens in the capsular bag; Vertical placement of the intraocular lens in the capsular bag
Intervention type(s): Procedure; Procedure
Intervention description(s): The eyes will be randomized (1:1) using a dedicated computer programme prior to the start of the study to have a vertical or horizontal placement of the intraocular lens in the capsular bag. The 0 and 180 degrees will be marked on the slit lamp prior to the surgery. The axes of the IOL will be orientated in reference to the midpoint of the optic haptic junction of the IOL. the fellow eye will receive the opposite placement (horizontal or vertical) of the IOL.; The eyes will be randomized (1:1) using a dedicated computer programme prior to the start of the study to have a vertical or horizontal placement of the intraocular lens in the capsular bag. The 0 and 180 degrees will be marked on the slit lamp prior to the surgery. The axes of the IOL will be orientated in reference to the midpoint of the optic haptic junction of the IOL. the fellow eye will receive the opposite placement (horizontal or vertical) of the IOL.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Fellow eye comparison when one eye has the intraocular lens placed in horizontal and other in vertical axis.
Masking: Single (Participant)
Primary purpose: Other
Keywords: cataract; pseudophakia; intraocular lens; ciliary sulcus; anatomy