There is a huge need to perform high volumes of surgery in sub-Saharan Africa, to tackle the backlog of avoidable blindness. There is a great need to train many eye surgeons safely, efficiently, effectively, and to an acceptable level of competence. There is also a need to maintain and improve the quality and outcomes of surgery. Currently, surgical training is often conducted using the traditional "apprentice model", where a trainee observes a qualified surgeon and learns from them, and then the surgeon supervises the trainee performing surgery on a patient. We believe that this conventional model has substantial limitations and drawbacks, making surgical training less efficient and less safe. We will test the hypothesis that intense modular simulation-based ophthalmic surgical education is superior to conventional training for the initial acquisition of competence. Pilot studies have been conducted in Malawi, Uganda, and South Africa to develop, test and refine aspects of modular simulation-based ophthalmic surgical training in cataract and glaucoma surgery. Assessment tools have been developed and validated for use in this simulation-based training (see Appendices 3a and 3b). Subsequent to these pilot and validation studies, we are now able to test the efficacy of focussed modular simulation-based ophthalmic surgical training in two separate parallel-group randomised controlled trials. We will conduct two independent trials of intense simulation-based ophthalmic surgical education for training ophthalmologists in the procedures for cataract, and separately for glaucoma: the two leading causes of blindness in sub-Saharan Africa. Trainee eye surgeons will be randomised to the 'intervention' of focussed simulation-based surgical training (in addition to, and as an enhancement to conventional training), or to the 'control' group of current conventional training alone. The 'control' group participants will receive the same simulation training, only after a period of one year. Follow-up assessments will measure whether the trainees have gained in surgical competence (objectively assessed using a specific and validated grading score), knowledge, their perceived confidence as a surgeon, and in terms of the benefit to their patients (the quality and quantity of surgery performed). All the training within the 'educational intervention' of this study will be performed using simulation. There is no testing or surgical training on patients within the study educational-intervention of both training trials. The only times when patients are indirectly involved is entirely as part of standard, regulated, and supervised clinical training within a Nationally accredited and registered ophthalmology training programme. When three anonymised and non-identifiable recordings of cataract surgical procedures are video-recorded (at three months, year one, and then another three at fifteen months), patients will be informed of the planned recording, and invited to sign a standardised informed consent as for any clinical image recording within standard clinical practice. Live surgery recordings or assessments for the GLASS trial intervention and control groups will be conducted in individual circumstances where the local Consultant Ophthalmologist deems the participant competent to perform (and record) SUPERVISED live surgery during the year post-intervention.